not so much.... As.. 的用法请教

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.

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

so much的位置一定要靠近修饰的对象，比如这里的is

这里so much和but不是什么变体，应该是XX is not A but B，so much只是强调is的程度