Boston is close to an ocean. Boston is at a low elevation. Boston is near many mountains. Boston is far north of the equator.
I gave my students this multiple choice question: During most of the year, the air over Boston, Massachusetts, contains a high amount of moisture. Which of the following best explains why there is a high amount of moisture in the air?

Only one answer is correct among these 4 choices:
- Boston is close to an ocean.
- Boston is at a low elevation.
- Boston is near many mountains.
- Boston is far north of the equator.

Could you tell me which one is correct?

Boston is close to an ocean.