Which of the following is not a reason a patient may complain that a newly prescribed drug is not doing what the doctor told her it would? 

A. The dosage may need to be changed.
B. The patient is not taking the medication as prescribed.
C. The drug has reached therapeutic level.
D. The wrong drug was dispensed.
E. The drug is working, but the patient does not understand how it works.

C. The drug has reached therapeutic level.
If a drug has not yet reached its therapeutic level, it may not be working yet, but a drug that has reached its therapeutic level should be working.