How is the use of hydroelectric power related to the sun? a. The sun powers the water cycle.
b. Solar cells collect hydroelectric energy.
c. Hydroelectric power can only be collected in sunlight.
d. Sunlight combines atoms in the air to form molecules of water.

the answer is A

Explanation:

The sun powers the water cycle and creates precipitation and the dams run off of water from the rain added to the river or lake.

i believe the correct answer from the choices listed above is the first option. the scientists need to look at the   validity of data, claims, hypotheses, and observations before  developing an argument. they base their arguments on facts that are present and they make sure they have proofs. 

explanation:

trachea, alveoli, lung capillaries, arteries