Question

a drug that increases the action of the central nervous system, the heart and other organs.

placebo

depressant

activant

stimulant

Explanation:

A placebo is an inactive substance with no therapeutic effect. A depressant slows down bodily functions. "Activant" is not a standard term for such drugs. A stimulant is defined as a drug that increases the activity of the central nervous system, heart, and other organs, matching the description.

Answer:

Stimulant