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

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

OA IS A WHY IS C INCORRECT