I doubt it would be A and B is missing the word "is" I'm quite sure C is a complete sentence
I feel that the answer would be B. Singing and upbeat song.
Answer:
The answer is the first one.
Explanation:
It says that they are in the deepest part of the ocean. Humans lungs can only survive half of that or 1/4 we don't have enough oxygen to do that. So for that the answer is the first one.
