Atoms with a(n) covalent bond share electrons.
B. A mushroom. It is alive.
Not A because it is only a part of an organism
Not C or D because they are not alive. An organism must be able to live on its own, eat somehow (in this case the mushroom is a decomposer), and reproduce. Mushrooms release spores which are like fungal seeds.
The species is specially Darwin Finches and this phenomenon is known as divergent evolution.
Im not sure if thats how it really works but if it did, either it would have to be very minimal to reduce overheating or it's just the bottom few layers of skin keeping the heat in while the muscles contract and retract.