The Major Problem with Drug Treatments Involving Disulfiram, Naltrexone, or Methadone

The major problem with drug treatments involving disulfiram, naltrexone, or methadone is that ______.

A) they cannot be given to patients for long periods of time
B) they only work on about half the patients to whom they are given
C) they produce tolerance to an even greater degree than some of the substances they are attempting to replace
D) patients can choose not to use them as required, rendering them useless