Answer:
B) The warm, moist Pacific air rises and cools, releasing precipitation as it moves up the windward side of the range, and this cool, now dry air mass heats up as it descends on the leeward side of the range
Explanation:
The air masses that have formed over the Pacific and move toward the western coast of the United States are warm and moist ones. As they reach the coastline they continue into the mainland, but only to come upon a natural barrier, a north-south mountain range. The warm and moist air starts to move up and starts to cool off, and as it does, condensation occurs, thus the windward side of the mountain range gets a lot of precipitation. The cool, but now dry air continuous its movement across the mountain range, and moves down its leeward side. As it moves down on the leeward side it heats up again, so it becomes a warm and dry air mass. This makes the leeward side very dry, so it is no wonder that it is dominated by desert and semi-desert.