问一道有争议的题目

Research during the past several decades on the
nature of language and the processes that produce and make it understandable
has revealed great complexity instead of underlying simplicity.

A.     
that produce and make it understandable has revealed great
complexity instead of underlying simplicity

B.      
of producing and understanding it have revealed not
underlying simplicity but great complexity

C.     
by which it is produced and understood has revealed not
underlying simplicity but great complexity

D.     
by which
it is produced and understood have revealed great complexity rather than
underlying simplicity

E.      
by which
one produces and understands it have revealed great complexity instead of
underlying simplicity

这题的答案是A，但是个人倾向于C

暂时不论not but 和instead of谁比较好的问题（后加N)都一样

问题是A中的produce 后面应该加一个it吧，这和make it understandable明显不可以共用宾语嘛

把C排掉的人大多数说是被动加上句意不通（因为说it is produced by the processes说不通）但我觉得很通啊。。。