CR - Argument using reverse causation

The correct answer is E. In order to determine whether the conclusion is true you need to answer the following question: Is scurvy the cause or the effect of the low concentration of vitamin C in blood?

OA is E

A scientist finds that sailors who have scurvy usually also have low vitamin C concentrations in their blood. The scientist concludes that vitamin C prevents scurvy in sailors.

There is no mention of the amounts of vitamin C; the scientist doesn’t argue that more vitamin C means greater protection against scurvy in sailors, so choice A is not assumed.

Curing scurvy is different than preventing it; choice B is outside the scope of the argument.

Other diseases have nothing to do with preventing scurvy, so choice C is incorrect.

Choice D is too extreme; the scientist doesn't need to assume that high vitamin C levels prevent scurvy in absolutely every case.

Choice E is a valid assumption; a correlation between vitamin C and scurvy could mean two things; that scurvy affects vitamin C concentration in the blood, or that vitamin C concentration affects the likelihood of contracting scurvy. Since the scientist is stating that the second scenario is true, he is assuming that the first scenario, that contracting scurvy decreases vitamin C concentration, is not true.

Choice E is correct.

karthikpandian19 wrote:A scientist found that sailors who get scurvy, a disease that affects the mucous membranes, tend to have lower concentrations of vitamin C in their blood than do those who do not develop scurvy. Based on this information, the scientist concluded that vitamin C protects against scurvy.

The scientist’s conclusion depends on which of the following assumptions?


(A) A very high blood concentration of vitamin C protects against scurvy more effectively than does an average concentration of vitamin C in the blood.

(B) Treatment for vitamin deficiency cures scurvy.

(C) A sailor who has a low concentration of vitamin C in the blood is susceptible to many diseases affecting the mucous membranes.

(D) People with high concentrations of vitamin C in the blood cannot develop scurvy.

(E) Scurvy does not cause low concentrations of vitamin C in the blood.