due to the rainshadow effect, which side of the cascades has the driest climate?\nwest\neast

Brief Explanations:

The rain - shadow effect occurs when moist air is forced to rise over a mountain range. As it rises, it cools and condenses, releasing precipitation on the wind - ward side (usually the west side for the Cascades with moisture coming from the Pacific). By the time the air reaches the leeward (east) side, it has lost much of its moisture, resulting in a drier climate.

Answer:

B. East