Antigens are A) proteins found in the blood that cause foreign ...

[futuristic]

Antigens are
A) proteins found in the blood that cause foreign blood cells to clump.
B) proteins embedded in B cell membranes.
C) proteins that consist of two light and two heavy polypeptide chains.
D) foreign molecules that trigger the generation of antibodies.
E) proteins released during an inflammatory response.

[aero]

I remember it was D