Biologist: In Region X, the average horn mass and body length of adult

Explanation

Let's go through the passage and label the parts.

Part	Function
Biologist:	author
In Region X, the average horn mass and body length of adult bighorn sheep has dropped over the past several decades.	statement of fact
The cause is probably regulations prohibiting hunting of smaller animals.	main conclusion
These regulations have undoubtedly given smaller sheep an advantage in surviving to a reproductive age.	supporting information
Therefore, genes for smaller adult size most likely have spread through the population.	intermediate conclusion

It's a little tricky to decide whether "The cause is probably regulations prohibiting hunting of smaller animals," or "Therefore, genes for smaller adult size most likely have spread through the population," is the main conclusion.

At the same time, by noticing that "These regulations have undoubtedly given smaller sheep an advantage in surviving to a reproductive age. Therefore, genes for smaller adult size most likely have spread through the population," supports "The cause is probably regulations prohibiting hunting of smaller animals," we can decide that "The cause is probably regulations prohibiting hunting of smaller animals," is the main conclusion since it is supported by other statements in the passage but does not support anything else.

A The first is the main conclusion; the second is an observation for which a causal explanation is presented.

We could argue that the second part of this choice is correct since, in a way, "genes for smaller adult size most likely have spread through the population," is explained by "These regulations have undoubtedly given smaller sheep an advantage in surviving to a reproductive age."

However, this choice has a clear failure point in that the first statement is not a conclusion. It's just a fact about a phenomenon.

Eliminate.

B The first is a premise supporting the second; the second is the main conclusion, but not the only conclusion.

This choice is tricky because the second boldfaced portion could seem to be the main conclusion because it appears at the end of the passage and is preceded by "therefore." So, we could decide that the second boldfaced portion is the main conclusion and that the first boldfaced portion provides support since it's at the beginning of the passage.

However, as we discussed above, the second boldfaced portion is an intermediate conclusion rather than the main conclusion.

Also, the first boldfaced portion merely describes the situation and does not support the second.

Eliminate.

C The first describes a phenomenon for which the main conclusion presents an explanation; the second is a subsidiary conclusion supporting the main conclusion.

The first does describe a phenomenon for which the main conclusion, "The cause is probably regulations prohibiting hunting of smaller animals," presents an explanation.

Also, as we discussed above, the second is an intermediate, or subsidiary, conclusion that supports the main conclusion.

Keep

D The first is a subsidiary conclusion that supports the main conclusion; the second is a premise that independently supports the main conclusion.

This choice is almost completely incorrect since the first is not a subsidiary conclusion and does not support any conclusion and the second is an intermediate conclusion and thus does not support the main conclusion "independently." Rather, it supports the main conclusion by following from "These regulations have undoubtedly given smaller sheep an advantage in surviving to a reproductive age."

However, notice that the question-writer did make this choice a little tricky because the first part of this choice correctly describes the second boldfaced portion and because the second part of this choice is somewhat correct in that the second boldfaced portion does support the main conclusion. So, the question-writer made it possible that, if we're not careful, we could be tempted to choose this choice.

Eliminate.

E The first suggests a causal explanation for a phenomenon described by the main conclusion; the second provides further evidence to support that explanation.

This choice is incorrect. At the same time, it's interesting to see how the question writer made this choice tricky.

The first boldfaced portion is the phenomenon rather than the explanation for the phenomenon, but if we're not careful, we could see "phenomenon" in this choice and think that it correctly describes the first boldfaced portion.

Also, the second boldfaced portion does help to support the explanation.

So, this choice is a good example of an incorrect boldfaced answer choice that can trip us up if we fail to keep thing straight.

Eliminate.

Correct Answer
_________________

In (C), "body length of adult bighorn sheep has dropped over the past several decades" is a phenomenon. "genes for smaller adult size most likely have spread through the population" is the subsidiary conclusion. The conclusion is "These regulations have undoubtedly given smaller sheep an advantage in surviving to a reproductive age". Therefore, option (C) is correct.

­MartyMurray Great explanation! I did get this one right. However, I chose C by method of elimination.

Can both of you pease review my answer? MartyMurray KarishmaB Thank you.

A. the second is an observation for which a causal explanation is presented. (Incorrect, second is an intermediate / subsidiary conclusion)
B. The first is a premise supporting the second (Incorrect, the first one is not a premise)
D. the second is a premise that independently supports the main conclusion (Incorrect, the second one is not a premise either)
E. the second provides further evidence to support that explanation  (Incorrect, the second one is not an evidence)
C. the first describes a phenomenon for which the main conclusion presents an explanation; the second is a subsidiary conclusion supporting the main conclusion (Close enough.)

I thought that the first BF is the main conclusion.
"The cause is probably regulations prohibiting hunting of smaller animals" - sounded like the premise to the first BF
"These regulations have undoubtedly given smaller sheep an advantage in surviving to a reproductive age." - further premise.
2nd BF uses "Therefore", definitely a conclusion. In this case, it is an intermediate conclusion.

 ­

Correct.

Correct.

Well, the second does provide support for the main conclusion.

However, it's not "a premise that independently supports the main conclusion" because it's an intermediate conclusion, rather than a statement of fact that stands on its own.

The second actually does support the explanation, even though the second is itself an intermediate conclusion.

So, what you said here isn't really correct.

This choice isn't just "close enough." It's spot on.

It's not though. It's a statement of fact about horn mass and body length.

This statement about the cause doesn't support the information about the mass and length. So, it's not a premise. We have to consider what supports what logically, rather than consider "sound."

This statement doesn't support the statement about the mass and length either.

­This is correct.­
_________________

­But It seems from the passage that 1st cause is described  and further upon analysis of the cause the author reaches a conculsion.
The conclusion reached is  genes for smaller adult size most likely have spread through the population.

How can we be sure that it is not the main conclusion of the passage
Please explain the gap in my understanding