This looks like there should be a list but i had this question in health before and the answer is virus cultureing.
Answer:
b
Explanation:
its not because you are smoking it is secondhand smoke
(the answer is b)it coulve been a but it say "only" and stress has a lot of effects on the body and c and d are answers to trick you but you have to pay attention to what it actually states
The answer is C. Medical technicians
