You are presented with the question "What are molecules that the defense system recognizes as foreign to the body?" and the following answer choices: 
- Allergies
 - lungs
 - antigens
 - bacteria
 - parasites
 - atoms
 - red blood cells
 - acetic acid

Now knowing that antigens are molecules that the immune system recognizes as foreign to the body and children are born with an immature immune, or defense, system, choose the best answer.


 

   antigens      