Why is agricultural production in China distributed in this way?

A.

Much of western China is covered by dense rain forests.
B.

Much of western China is mountainous and has a desert climate.
C.

The Huang He frequently floods, destroying farmland in western China.
D.

The Gobi Desert covers western China, making it incapable of supporting farms.

B. Much of western China is mountainous and has a desert climate. This geographical feature makes it difficult for agricultural production to thrive in these areas, leading to a distribution of agricultural production in regions with more suitable environments for farming.