Mekong River is rich in resources.

The agricultural regional type of Mekong River basin is rice planting (monsoon paddy field agriculture), and its advantages are: rain and heat at the same time, sufficient water resources and convenient irrigation; Long production history and rich cultivation experience; Rice is the main food for local residents; However, the degree of agricultural mechanization is low, the level of science and technology is low, and the commodity rate is low.

So choose: C.