We have to validate that the number of women graduating from medical school annually doubled from 1950 to 2000.
For this we have to prove that, the other students graduating with that of female candidates are same, only then it will show that the number of female students have significantly increased.
(A) The number of women who were accepted to medical school but chose not to enroll (We can't validate that number of female students have increased from this information) (Incorrect)
(B) The number of men who applied to medical school (we need the graduating students data not those who applied) (Incorrect)
(C) The number of female medical school graduates who became researchers rather than practicing physicians (We can't infer that the female students number have increased from this) (Irrelevant)
(D) The number of men graduating from medical school annually (Yes, the number of other students who graduated from medical school will give significant report whether the female candidates have increased or not)
(E) The number of men graduating from college annually (We are talking about Medical Schools not College)
Answer is D.
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