I believe the answer is D. We do the work so you don't have to but dont quote me on that!!!! hope this helped!!!!
The correct answer is biological.
Biology deals with the inner workings of our body - so, if something is the result of hormones and other physiological processes, then it will definitely be related to biology. The other options have more to do with the environment, rather than with the body itself.
Not much fam, hb yourself
I'd say keeping the T cell count high because these are the cells that fight viral infections (HIV is one of them).
Answer:

Hope it helped,
Happy homework/ study/ exam!
People with anemia and blood conditions