求助 a portion of the capital 谓语动词用第几人称

求助 a portion of the capital 谓语动词用第几人称？

capital 不是不可数名词吗？应该用第三人称才对吗？ 可是大全上答案却是谓语动词复数...

恍然大悟，太谢谢了。把题贴出来，大家也看看吧。

      Art museums do not usually think of their collections as capital or consider the interest income that would be generated if a portion of the capital would have been invested in another form.

(A) be generated if a portion of the capital would have been

(B) have been generated if a portion of the capital would have been

(C) be generated if a portion of the capital were

(D) be generated if a portion of the capital was

(E) be generated if a portion of the capital had been

答案：C

答案：C