请教新东方逻辑一题

Dear all, Please help answer the question below from XDF's logic excercise.

In a political system with only two major parties, the entrance of a third-party candicate into an election race damages the chanc es of only one of th etwo major candidates. The third-party candidate always attracts some of the voters who might otherwise have voted for one of the two ajor candidates  but not voters who suppoert the other candidate. Since a third-party candidacy affects the two major candidates unequally, for resons neither of them has any control over, the practice is unfair and should not be allowed.

If the factual information in the passage above is true, whichof the following can be most reliably inferred from it

B, If, before the emergence of a third party, voters were divided equally between the two major parties, neither of the major parties is likely to capture mch more than one-half of the vote

C, A third-party candidate will not capture the votes of new voters who have never voted for candidates of either of the two major parties..

I chose C yet the answer is B. Can anyone kindly explain why? Thks for ur help in advance!

文中没有提到“第三方是否能得到未投票人的支持”问题。因此，无法确定C的真假。

B正确，文中说“第三方只能夺取一方票数”，也就说明了，如果原来双方各50%，第三方夺取了一方的10%，那么比例将是10%，40% 和50%，哪个部分也没有超过50%

谢谢xfi883！