Reasonable arrangement of farming activities

The measures to control soil erosion in the Loess Plateau are: on the one hand, combine biological measures such as planting trees and grass with projects such as repairing earth dams to control soil erosion; On the other hand, reasonable arrangements should be made for production activities, such as returning farmland to forests and grasslands on steep slopes, and reducing the number of grazing livestock in overgrazing areas.

So choose: a.