What area is busy with wheat stubble in the morning and cotton picking in the afternoon?

Proverbs show that both wheat and cotton are grown in this area. The typical agricultural regional types in the Pearl River Delta are monsoon paddy field agriculture and pond agriculture. Qaidam basin and southern Tibet valley are located in the Qinghai-Tibet Plateau, with high altitude and insufficient heat, which are not suitable for planting wheat and cotton. Weihe plain belongs to temperate monsoon climate with flat terrain, which is suitable for planting wheat and cotton.

So choose: D.