Which explains how the Sierra Nevada Mountains of California cause the southwestern United States to have a desert climate?
A. The mountains block warm moist winds from the Pacific Ocean. As the air rises, it cools and loses its moisture, leaving dry winds to blow over the southwest.
B. The mountains absorb excess heat energy from the sun, which warms the air over the southwest and causes the region to be a desert.
C. The mountains block warm moist winds from the Pacific Ocean. As the air rises, it heats up and loses its moisture, leaving hot, dry winds to blow over the southwest.
D. The mountains reflect excess heat energy from the sun, which warms the air over the southwest and causes the region to be a desert.

I think it's A.