OG 243,扶持一下，我分不清动词的单复数

243. Some scientists have been critical of the laboratory tests conducted by the Federal Drug Administration on the grounds that the amounts of suspected carcinogens fed to animals far exceeds those that humans could consume.

(A)  far exceeds those that humans could consume

(B)  exceeds by far those humans can consume

(C)  far exceeds those humans are able to consume

(D)  exceed by far those able to be consumed by humans

(E)   far exceed those that humans could consume

我选得是a，可是og的解释是exceed是复数，exceeds是单数，我不明白，那位能指点一下？