Answer:
No doubt: A
Step-by-step explanation:
Reptiles require a good body temperature, because their blood is highly influenced by the environment's own temperature. That's why people talk about cold blood on reptiles. They rely on a certain temperature to warm their own body, and it certainly becomes indispensible to them, because slight changes affect their whole body. This is not a very complete explanation, but, in the end, keep that in mind. I just hope I could help :)