Which statement best describes antibodies?

• A. An antibody is a protein produced to bind and neutralize antigens.
• B. Antibiotics are produced by white blood cells to kill bacteria.
• C. Antibodies trigger antigens to appear on cells.
• D. Antibodies are the same as antigens.

Answer: (A)

Antibodies are proteins produced by immune cells to recognize and neutralize foreign substances called antigens. When an antibody binds its specific antigen, it can block the pathogen from infecting cells or releasing toxins, and it also flags the invader for other parts of the immune system to attack through processes like opsonization or complement activation. This makes antibodies a key defense that directly targets the harmful agent and helps coordinate the broader immune response. The statement captures both what antibodies are (proteins) and what they do (bind and neutralize antigens).

Antibiotics aren’t produced by white blood cells; they’re chemical compounds typically made by microorganisms to kill bacteria. Antibodies don’t cause antigens to appear on cells; antigens are the foreign substances that antibodies recognize. And antibodies aren’t the same as antigens; antibodies are the defensive proteins, while antigens are the substances that trigger an immune response.