need help for feifei-17

feifei 1-17.

Psychologist: Some astrologers claim that our horoscopes completely determine our personalities, but this claim is false, I concede that identical twins---who are, of course, born at practically the same time---often do have similar personalities. However, birth records were examined to find two individuals who were born 40 years ago on the same day and at exactly the same time---one in a hospital in Toronto and one in a hospital in New York. Personalities of these two individuals are in fact different.

argument 的推理：出生时的星位完全决定性格。作者提出反驳：生在T和NY的人性格就不同。言外之一认为：他们出生的星位时相同的。f否则，作者的反驳就是无力的。

这题B的迷惑性比较大。好像用取非很难判断。不知道别人怎么判断这种题目，我的方法比较笨，把两个并列起来，看哪个能单独存在。能单独存在的就是true assumption. 有没有人有比较好的方法？

Which one of the following is an assumption on which the psychologist’s argument depends?

(A) Astrologers have not subjected their claims to rigorous experimentation.

(B) The personality differences between the two individuals cannot be explained by the cultural difference between Toronto and New York.

(C) The geographical difference between Toronto and New York did not result in the two individuals having different horoscopes.

(D) Complete birth records for the past 40 years were kept at both hospitals.

(E) Identical twins have identical genetic structures and usually have similar home environments.


    查了查，这题没问过，（可能太小儿科了？）


但是我不明白assumption怎么能是C，geographic difference did not result in two individuals having DIFFERENT HOROSCOPES. 简言之，地理差异没使他俩有不同的星座！为什么B不对？！Desperately need your help.