A. Vast
The predicate adjectives are adjectives that change the subject. In this case, the subject is the Atlantic Ocean and so the adjective that modifies it is the predicate adjective. In this sentence, "vast" is the one that changes the Atlantic Ocean.
This answer is False. I just taken the test and that's the answer!
Background reshearch in a science project is basically just finding all about the project and making sure your soing it right.