GMAT Sentence Correction (SC) | Re: Some patients who do not respond therapies of depression may

Some patients who do not respond therapies of depression may simply have received inadequate treatment,having, for example, been prescribed a drug as a dosage too low to be effective or having been taken off a drug too soon.

A -- having, for example, been prescribed a drug as a dosage too low to be effective or having been
B -- having, for example, a drug prescription that was ineffective because the dosage was too low, or being
C -- as, for example, having too low of a dosage of prescribed