You are presented with the question "Plasma cells are activated B cells that secrete what?" and the following answer choices: 
- heat or cold
 - harmful substances
 - Leptospirosis
 - bioaerosols
 - protein molecules
 - Chemical energy
 - major threat to health
 - Veins and arteries.

Now knowing that plasma cells are activated B cells that secrete antibodies and antibodies are protein molecules, choose the best answer.


 

     protein molecules    