Question

multiple choice question
what is the third line of defense against pathogens?
adaptive immunity
external barriers
leukocytes, antimicrobial proteins, fever, and inflammation
need help? review these concept resources.

Explanation:

The body has three lines of defense against pathogens. The first line is external barriers (like skin, mucous membranes). The second line involves leukocytes, antimicrobial proteins, fever, and inflammation (innate immunity non - specific). The third line is adaptive immunity, which is specific and targets particular pathogens, involving lymphocytes (B and T cells) and antibody - mediated/humoral as well as cell - mediated responses. "External barriers" is the first line, and "Leukocytes, antimicrobial proteins, fever, and inflammation" is the second line. So the third line is adaptive immunity.

Answer:

A. Adaptive immunity