Answer:
A. He should make his research questions more concise
Step-by-step explanation:
As a result of getting dozens of different materials to work with based on his research question, "How are Blue whales important?", he should make his research question more concise.
He can ask the question, "why are blue whales important to ecology?" or "Why are blue whales important in the animal world?". These concise questions would help make his work easier as they are more specific.