I am pretty sure the answer is D (combination)
The ability to blend into the surrounding environment can come in handy when trying to avoid a predator, especially for those animals with little else in their defense arsenal.
1. air is warmed near earth's surface
2. water vapor rises and comes in contact with cooler air
3 water vapor condenses onto partials etc.
4 water enters the atmosphere through evaporation
5 clouds are born
warm air can “hold” more water vapor than cool air because as the air warms its molecules move farther apart, making room for more molecules. This leads to the idea that as air cools its molecules move closer together, “squeezing” out water vapor.