TASK DEFINITION: In this task, you are given a question and an answer, you would be asked to create the sentence based on the Question-Answer provided. It should be contained within the Question-Answer provided.
PROBLEM: Question: Living things on the ocean floor are known as? Answer: benthos

SOLUTION: Living things on the ocean floor are known as benthos.

PROBLEM: Question: What is the name of the location in which a stream or river starts? Answer: source

SOLUTION: Source is the name of the location in which a stream or river starts.

PROBLEM: Question: Which is the best explanation for how air masses move across the United States? Answer: The prevailing westerlies move air masses from west to east across the United States but may be deflected by the jet stream.

SOLUTION:
The best explanation for how air masses move across the united states is that the prevailing westerlies move air masses from west to east across the united states but may be deflected by the jet stream.