( Answer this Correctly Dont Answer if you don't know the answer )

1.) What is a cold blooded animal? ( I think it's Between B/D )
A. It is another term for vertebrate.
B. It is an animal with constant body temperature.
C. It is an animal which can maintain its body temperature
D. It is an animal whose internal temperature varies with the surrounding

2.) Which word refers to the underwater habitat for essential species of marine organisms?
A. Coral reefs C. Rainforest
B. Mangrove D.Tropics

( Would be better if there's a Explanation to your answer )