You are presented with the question "Active immunity is when an immune response occurs after a germ produces what?" and the following answer choices: 
- harmful substances
 - bioaerosols
 - rapid expansion
 - Allergies
 - anemia
 - it needs them
 - Chemical energy
 - memory cells

Now knowing that active immunity results when an immune response to a pathogen produces memory cells and pathogens are germs that cause disease, choose the best answer.


 

        memory cells 