Fact 1: Antigens are molecules that the immune system recognizes as foreign to the body. Fact 2: Antigens are proteins foreign to the body. Given the two facts above, what are antigens?

Pick from: (a). animals; (b). negative; (c). positive; (d). complex; (e). proteins; (f). PDAs; (g). humans; (h). parasites;
Answer:
(e).