Not so much ... as... 的结构是不是有一个变体是 Not so much ... but....， 我查不到这个用法，请教一下高人。

GWD有一个题，如下，选E， 不明白为什么不选A。

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.

A     an illness or a physical condition so much as a symptom of another problem that may simply be a reaction to certain medications

B     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

C     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

D     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