When You Walk into Your Next Class You See the Term

When you walk into your next class you see the term "psychotropic medications" written on the blackboard. You never know when such information might come in handy, so you look it up and find that it refers to

A) special placebo pills used in drug research.
B) chemical substances that affect our psychological state.
C) chemical substances that cause a psychedelic experiences.
D) special drugs designed to "turn off" genes thought to cause mental disorders.