Plants speed up the water cycle by removing carbon from the air. Plants start the water cycle when they make water in photosynthesis. Plants are part of the water cycle through the process of transpiration. Plants stop the water cycle because they absorb it and stop the flow to streams.
I gave my students this multiple choice question: Why should plants be included in investigations about the water cycle?

Only one answer is correct among these 4 choices:
- Plants speed up the water cycle by removing carbon from the air.
- Plants start the water cycle when they make water in photosynthesis.
- Plants are part of the water cycle through the process of transpiration.
- Plants stop the water cycle because they absorb it and stop the flow to streams.

Could you tell me which one is correct?

Plants are part of the water cycle through the process of transpiration.