­The evidence of the last 50 years in this country shows how unlikely

­The evidence of the last 50 years in this country shows how unlikely it is that the cost of treating any particular disease in the population at large will fall merely because of improvements in medical technology. For while medical technology advanced tremendously during that time, annual overall spending on disease treatment also rose dramatically. 

The conclusion of the argument is the following:

The evidence of the last 50 years in this country shows how unlikely it is that the cost of treating any particular disease in the population at large will fall merely because of improvements in medical technology.

The support for the conclusion is the following:

while medical technology advanced tremendously during that time, annual overall spending on disease treatment also rose dramatically

One issue with this argument that may jump out at us is that the conclusion is about "the cost of treating any particular disease" whereas the evidence is about "overall annual spending on disease treatment."

So, basically, the author has used evidence about an increase in TOTAL spending to support the conclusion that the cost of treating any PARTICULAR disease does not fall because of improvements in medical technology.

Using that evidence to support the conclusion is a questionable approach since the fact that overall spending increased does not necessarily indictate that the cost of treating any particular disease did not fall. After all, there could be many reasons why overall spending would increase even if the cost of treating specific diseases fell.

The argument is vulnerable to challenge on the grounds that it fails to take into account the possibility of change in each of the following EXCEPT 

This question is a Logical Flaw EXCEPT question. So, the correct answer will be the only choice that does NOT bring up a variable such that the argument is flawed because it fails to take into account the possibility that that variable has changed.

A. the average age of the population

The argument is flawed because it does not take into account the possibility of change in "the average age of the population."

After all, if the average age has increased, that change could be the reason why "annual overall spending on disease treatment ... rose dramatically."

So, if the average age of the popluation changed, it could be that the cost of treating any particular disease in the population at large DOES fall because of improvements in medical technology but overall spending increased anyway because the average age increased and older people used medical services more.

In that case, the argument's conclusion does not follow from the evidence.

Eliminate.

B. the value of money as a result of inflation

The argument is flawed because it does not take into account the possibility of change in "the value of money as a result of inflation."

After all, if the value of money has changed as a result of inflation, that change could be the reason why "annual overall spending on disease treatment ... rose dramatically."

So, if the value of money did change, it could be that the cost of treating any particular disease in the population at large DOES fall because of improvements in medical technology but overall spending increased anyway because the value of money changed as a result of inflation.

In that case, the argument's conclusion does not follow from the evidence.

Eliminate.

C. the size of the population

The argument is flawed because it does not take into account the possibility of change in "the size of the population."

After all, if the size of the population has increased, that change could be the reason why "annual overall spending on disease treatment ... rose dramatically."

So, if the size of the population changed, it could be that the cost of treating any particular disease in the population at large DOES fall because of improvements in medical technology but overall spending increased anyway because the size of the population increased and so there were more people spending on medical services.

In that case, the argument's conclusion does not follow from the evidence.

Eliminate.

D. the number of medical researchers

The argument is not flawed because it fails to take into account the possibility of change in the number of medical researchers.

After all, even if the number of medical researchers did change, a change in the number of medical researchers would not affect overall spending on treatment of disease. After all, current spending on disease treatment is not affected by the number of medical researchers working on future treatments.

So, a change in the number of medical researchers would have no effect on the support the evidence provides for the conclusion.

Thus, since this question is a Logical Flaw EXCEPT question, this choice is correct because it's the only one that does not highlight a flaw in the argument.

Keep.

E. the types of disease prevalent in the population

The argument is flawed because it does not take into account the possibility of change in "the types of disease prevalent in the population."

After all, if the types of disease prevalent in the population have changed, that change could be the reason why "annual overall spending on disease treatment ... rose dramatically." After all, the new types of diseases that are prevalent could be more expensive to treat than the ones  that were prevalent before.

So, if the types of disease prevalent in the population have changed, it could be that the cost of treating any particular disease in the population at large DOES fall because of improvements in medical technology but overall spending increased anyway because the types of disease prevalent in the population changed with the result that overall spending increased.

In that case, the argument's conclusion does not follow from the evidence.

Eliminate.

Correct answer: D­