求助 prep-2-54

54.Greatly influenced by the Protestant missionary
Samuel Kirkland, the Oneida was the only one of the five-nation Iroquois
League who sided with the colonists during the American Revolution.

(A) was the only one of the five-nation Iroquois
League who sided

(B) was alone of the five-nation Iroquois League
when they sided

(C) alone among the five nations of the Iroquois
League sided

(D) were the only ones out of the five nations of
the Iroquois League in siding

(E) only of the five-nation Iroquois League had
sided

答案C,为什么不能选A呢?难道是A中的who不对?

C中alone前面没有be动词啊