The water droplets that form clouds are so tiny that they remain suspended in the atmosphere. As these droplets bump into each other, they can combine to form larger droplets. When these droplets get too heavy to stay airborne, they fall back to Earth as rain. Ice crystals behave the same way, but produce snow or sleet. The water falling back to Earth is called precipitation. Precipitation returns the evaporated water that formed the cloud back to Earth’s soil and bodies of water. This critical step in the water cycle would not happen without clouds. Which of the following best describes why precipitation falls to Earth?

A
Water droplets or ice crystals heat up and become too warm to remain airborne.

B
Water droplets or ice crystals combine and become too heavy to remain airborne.

C
Water droplets or ice crystals are pushed out of clouds by wind in the atmosphere.

D
Water droplets or ice crystals move around a cloud until they build up enough energy to escape.