A hallucinogen is defined as...

• A. A drug that reduces anxiety.
• B. A drug that speeds up heart rate only.
• C. A drug that cures infections.
• D. A type of drug that causes changes in perception, thought, and feeling.

Answer: (D)

Hallucinogens are drugs that alter the way you perceive the world, think, and feel. This means you might experience changes in sight, sound, or sense of reality, along with unusual thoughts or emotional shifts. That set of effects defines what a hallucinogen does, setting it apart from drugs that simply reduce anxiety or calm you, drugs that speed up the body, or medicines that cure infections. So describing a hallucinogen as a drug that causes changes in perception, thought, and feeling best captures its characteristic effects.