The Development of Pharmaceuticals Specific to Substance Use Disorders Has

The development of pharmaceuticals specific to substance use disorders has been delayed because

A) those regions of the brain involved in the addictions are so widespread that no single pharmaceutical, or combination of pharmaceuticals, can work on every one.
B) pharmaceutical companies view the demand as too limited to make the development of such medications worthwhile.
C) the current generation of medications is sufficient to treat conditions associated with substance use disorders.
D) there are new medications under development, which should revolutionize the treatment of substance use disorders.