LSAT-18-2-20原题不全，求助

snow_mountain

20. Of the ten professional tennis players who
are generally considered the greatest of all
time, six had no brothers or sisters. However,
only a small portion of the general population is
made up of such "only children." Clearly, if you
are a professional tennis player, you have a
better chance of being considered among the
greatest if you are an only child.
Which one of the following, if true, would
undermine the argument in the passage?
(A) Some great tennis players never play
professionally.
(B) Ascribing "greatness" to tennis players is
necessarily subjective.
(C) Among all professional tennis players, seven
(D) An only child tends to be better at
individual sports than at team sports.
(E) Parents who have only one child have more
time to invest in the child's tennis career than
do other parents.

答案居然是C。 这类题目一点思路也没有。谁有原题补充一下，或者提供一下思路，看看可能的答案是什么。