Multiple choice

An antigen is

  1. opposite of an antibody

  2. residue of an antibody

  3. stimulus for antibody formation

  4. result of antibody

Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

An antigen is a substance (usually protein or polysaccharide) that stimulates antibody formation when introduced into the body. It is the triggering molecule for immune response, not the antibody itself.