Answer:
The water on earth changes forms as it moves from one reservoir to another.
Explanation:
The other two answer choices are
1: as water moves through an ecosystem, its energy is lost between trophic levels.
2:The water on earth changes forms as it moves from one reservoir to another.
and
3: Water in the atmosphere must be converted to another chemical before animals can use it
The correct answer of course would be answer choice 2. It does change forms as in states of matter from liquid to gas (water vapor) to solid (ice) and back again. This is the best summery of what the water cycle means.
1 is incorrect because it violates the law of conservation of energy. Water has nowhere to go so it stays on the surface of the earth.
And three is wrong because it simply does not describe the water cycle.
