Contour plowing, no-till planting, and planting trees to serve as wind buffers are all methods used to a. reduce erosion b. farm organically c. conserve water d. increase crop yields

A. reduce erosion

Explanation:

Erosion is the wear or denudation of soils and rocks that produce different processes on the surface of the Earth. Erosion involves movement, transport of material, in contrast to the alteration and disintegration of rocks, a phenomenon known as weathering and is one of the main factors of the geographical cycle. Between the erosive agents they are the circulation of water or ice, the wind, or the thermal changes. The erosion produces the relief of the valleys, gorges, canyons, caves and tables, and can be increased by human activities.

(d). gave voting rights to free african americans and white women.