By components do you mean organs? If so...
1. Brain - gives demands ands orders to all of the body to function properly
2. Heart - pumps blood, and keeps the organism receiving the blood alive
3. Skin - protects the tissue from UV Rays that may be harmful
D Type. He is changing the type of activity he is doing for his bike-riding routine.
The answer among the choices is letter A. Sterols is a lipid that doesn't contain a glycerol backbone because it is mostly unsaturated. It can be commonly found on fungi, plants, and animals as an important organic molecule. I hope my answer helps you.
