An antigen is
A) any molecule that can elicit an immune response.
B) a protein only.
C) a nucleic acid only.
D) a protein or nucleic acid.
E) a protective protein that the immune system produces.

Question

Quizplus · Accepted Answer

An antigen is any molecule that can elicit an immune response, including proteins, nucleic acids, carbohydrates, and lipids. Therefore, option A is the correct answer. B, C, and E are incorrect because they are either too narrow (proteins only) or incorrect (protective protein that the immune system produces). D is partially correct but does not fully capture the broad range of molecules that can act as antigens.

An Antigen Is