jaituteja wrote:
Unable to understand why D is incorrect..???
Also,what is the relevance of this statement in the passage..
"Only genetic throwbacks of this species had colored wings."
Doesnt it say the "only genetical moths can have coloured wings".???
Awaiting experts revert..
Hi jaituteja.
I'm happy to help.
First of all, I think your question is
"Why D is correct?" Is that true?. Anyway, I will analyze the question as followings:
ANALYZE THE STIMULUS:Fact: Before preindustrial England: Moth was entirely white. After the industrial revolution: most members of moth developed gray wings
Fact: white wings helped moths to blend in with the pale rocks and white sand of the coast
Fact: the soot of the industrial revolution caused the white rocks and sand (the moths’ habita) to turn gray.
Conclusion: The change in wing color must be attributable to the soot of the industrial revolution.
To make the stimulus clearly, I use a diagram below:
Before:
A caused B
After:
C changed A to A*
…. changed B change to B*
Conclusion: C must cause B change to B*Assumption: A* & B must have correlation. This is
a bridge to connect C to B*
Apply to this question:Before:
White rock & sand caused moth's wings were white
After:
The soot changed white rock & sand to gray rock & sand
…………. changed white wings moths to gray wings moths
Conclusion: The soot causes moths’ wings turned gray.Assumption: the white wings moths MUST have to adapt new environment – Gray rock & sand.
ANALYZE EACH ANSWER:(A) Gray moths can fly faster than white moths and are better able to avoid birds.
Wrong. Clearly out of scope.
(B) The soot of the industrial revolution is the only reason why the rocks and sand turned gray.
Wrong. SHELL GAME. It’s very tempting. Some of you may think “
oh, this is defender assumption, bingo”. But it’s wrong. This question is about
“Supporter assumption”. Please see the diagram, even though the soot is the only reason that turned rocks and sand to gray. How does it affect the conclusion “the soot caused moths’ wings turned gray”?
This option only shows the link between the soot and the color of rocks and sand, but it does not connect shoot to color of moth's wing. You can see the diagram: “C caused A to A*”. That’s it. You need “a bridge” – “A* - B” to connect “C also caused B to B*.
(C) The rocks and sand were just as gray in preindustrial England as they are today.
Wrong. It does not help. “as they are today” does not make any point.
(D) Moths that are best able to blend in with their habitats possess an evolutionary advantage.
Correct. This is exactly the bridge you need. D says “moths were able to adapt new environment by changing their wings’ color”.
(E) The presence or absence of factories in England held an implication for the diet of birds that lived on the coast.
Wrong. Out of scope.
Hope it helps.