Question

how is the sun involved in the hydrologic cycle?
it cools the earth. it powers the cycle.
it is not involved, at all. it provides nutrients.

Explanation:

The sun's energy is crucial for the hydrologic cycle. It heats water on Earth's surface (like oceans, lakes), causing evaporation. This evaporation is a key part of the cycle. So, the sun powers the hydrologic cycle. It doesn't cool the Earth in the context of the hydrologic cycle's main function here, and it doesn't provide nutrients (nutrients are more related to soil, fertilizers etc. in biological systems, not the sun's role in the hydrologic cycle).

Answer:

It powers the cycle.