Plasma cells are activated B cells that secrete antibodies, and antibodies are protein molecules. Given these facts, plasma cells are activated B cells that secrete what among the following options:
- heat or cold
 - harmful substances
 - Leptospirosis
 - bioaerosols
 - protein molecules
 - Chemical energy
 - major threat to health
 - Veins and arteries.


 

     protein molecules    