I think that the answer is D. Dieting because dieting helps your body eat more things that are good for it and, less things that are bad for it. It can make your skin clearer, and help you feel good overall which is a physical health help trait.
The main thing would be to not smoke. But also if you are around someone who smokes, try to limit interaction with them while they are smoking. second hand smoke can be just as deadly. Also doing things like using smoke free facilities, like smoke free hotel rooms and restaurants.
Different genes control the development of different characteristics of an organism.
