Which of the Following is an Exogenous Antigen

Question

Which of the following is an exogenous antigen?
A) a bacterium inside a cell
B) a virus inside a cell
C) a bacterium outside a cell
D) a noninfected human cell
E) the malaria parasite inside a red blood cell

Accepted Answer

An exogenous antigen is an antigen that enters the body from outside and triggers an immune response. Among the given choices, only a bacterium outside a cell is an exogenous antigen.