Fact 1: Antigens are molecules that the immune system recognizes as foreign to the body.

Fact 2: Heavy metals are, in general, foreign to the body.

Given the two facts above, answer the question "Heavy metals are _." with the following options: 
- emissions
 - dangerous
 - bent
 - homogenous
 - antigens
 - vehicles
 - fossil fuels
 - heat energy


 

     antigens    