Can Someone Please Help Me For 10 Points.

John steps outside and observes that clouds have started to form in the sky, and it looks like it could rain. Which of the following is the best way to explain why the clouds have formed?

A. The temperature of the air is below zero.

B. There is a low amount of moisture in the air.

C. The warm, wet air in a low pressure system has risen up and cooled down.

D. The wind is traveling at a slow speed.