You are presented with the question "passive immunity lasts only as long as the antibodies survive where?" and the following answer choices: 
- cows
 - heat
 - skin
 - Mitosis
 - blood
 - humans
 - Summer
 - animals

Now knowing that passive immunity lasts only as long as the antibodies survive in body fluids and inside the body, blood is normally a fluid, choose the best answer.


 

     blood    