Heavy metals are _.
Options:
- (A) emissions
- (B) dangerous
- (C) bent
- (D) homogenous
- (E) antigens
- (F) vehicles
- (G) fossil fuels
- (H) heat energy
Hmmm, let me think. I don't want to be wrong, so I got to be careful.
Antigens are molecules that the immune system recognizes as foreign to the body. Heavy metals are, in general, foreign to the body. Heavy metals are antigens. The answer: (E).