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

答案是E，我的答案是C。

 not so much...but 固定搭配

我就是不知道那个symptomatic 后面怎么可以加of

c实在太wordy了

d前后主语一致，后半句不应该有it主语