请教大全一题关于同位语～ 大家来看看

chaomat1988

1.        n large doses, analgesics that work in the brain as antagonists tocertain chemicals have caused psychological disturbances in patients, whichmay limit their potential to relieve severe pain.
(A) which may limit their potential to relieve
(B) which may limit their potential for relieving
(C) which may limit such analgesics’ potential to relieve
(D) an effect that may limit their potential to relieve（E）
(E) an effect that may limit the potential of such analgesics forrelieving
答案选E，，，我选了A ，，，，WHICH修饰DISTURBANCES为什么不行啊，，，IN PATIENTS是修饰DISTURBANCES的吧。。。。                     如果是E的话，，同位语能修饰前句子结尾的名词吗？ 我记得之能修饰前句的主语？  大家指点下

mlvince

which就近指代patients了吧