According to the author of "Mysterious Oceans," what is one of the mysteries of the sea?

A. Only about five percent of the world’s oceans have been studied fully.

B. Some sea creatures live where there is no sunlight and hardly any food.

C. The Giant Squid was not seen alive until just a few years ago.

D. There are different kinds of starfish.

A

Explanation:

The other answers hardly can be called mysteries.

B is a known fact

C and D are statements

So the reason why the author talks about the mysteries of the sea is simple: only 5 percent of the world´s oceans have been studied, therefore the other 95 percent remains a mystery.

Sorry if im late lol ,

the answer is D.  

There are different kinds of starfish.

Explanation:

b. some see creatures live where there

why biographies are better than plays

explanation someone is saying they like biographies better