Which statement correctly describes the relationship between antigens and antibodies?

• A. An antigen triggers an immune response; an antibody is produced to bind and neutralize antigens.
• B. An antigen is produced by antibodies.
• C. Antibodies trigger antigens to destroy themselves.
• D. Antigens and antibodies have identical roles.

Answer: (A)

Antigens are foreign substances that trigger an immune response. When an antigen enters the body, B cells respond by producing antibodies that are specific to that antigen. These antibodies bind to the antigen, neutralizing it directly or marking it for attack by other parts of the immune system. This relationship—an antigen prompting antibody production to bind and neutralize it—describes how the adaptive immune system targets invaders. The other ideas are inaccurate: antibodies aren’t produced by antigens, they don’t cause antigens to destroy themselves, and antigens and antibodies don’t have identical roles.