请教一到语法题，实在搞不懂

Q30L)((((((((

Most insomnia is not an illness or a physical condition so much as a symptom of another problem that may simply be a reaction to certain medications, anxiety about travel, or stress before a job interview.

1. an illness or a physical condition so much as a symptom of another problem that may simply be a reaction to certain medications
2. an illness or a physical condition so much as symptomatic of another problem that may be a simple one, like a reaction caused by certain medications
3. so much an illness or a physical condition but a symptom of another problem that may be as simple as when certain medications cause a reaction
4. so much an illness or a physical condition, but it is a symptom of another problem, maybe a simple one like certain medications causing a reaction
5. so much an illness or a physical condition but symptomatic of another problem, maybe simply a reaction to certain medications

选哪一个呢？

I think A is the best.

yes, E is correct

This is a fixed combination:

XXX is not much a XXX but a XXX

so much an illness or a physical condition but symptomatic of another problem, maybe simply a reaction to certain medications

但是symptomatic of another problem做什么成分

the sentence is similar to the following one (although not  exactly, I just want to make it simple to you):

I am not an American but a Chinese.

what do we call it in Chinese? 表语?

Whatever that is, not important, the important thing is the right structure.

I think A is correct. "not so much...as..." is different from "XXX is not much a XXX but a XXX" or "XXX is not a XXX but a XXX."

may be C is correct answer