Some patients who do not respond to therapies for depression

Some patients who do not respond to therapies for depression may simply have received inadequate treatment, having, for example, been prescribed a drug at a dosage too low to be effective or having been taken off a drug too soon.
A. having, for example, been prescribed a drug at 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----------->being should be avoided
C. as, for example, having too low of a dosage of a prescribed drug for it to be effective, or being --------------->as and for example should not be used simultaneously
D. when they have, for example, been prescribed too low a drug dosage to be effective, or were --------------->been and were breaks paralleism
E. for example, when they have a drug prescription with a dosage too low to be effective, or been