During the water cycle, the sun's energy evaporates water from the surface of Earth. This water is the source of

The answer is C. Precipitation, throughout the water cycle water is flowing through our stratosphere. At one point in the water cycle water builds up into clouds, and then that water become heavy forming droplets, which then fall to the Earth and form pools of water. Then when the Sun heats the water the water evaporates and goes through the water cycle in endless loop.

the solute can move "downhill," from regions of higher to lower concentration, relying on the specificity of the protein carrier to pass through the membrane. this process is called passive transport or facilitated diffusion, and does not require energy.