After harvesting their main crops, such as corn and wheat, many farmers plant a second crop called a cover crop. this cover crop grows during the fall and winter and is then plowed over in the spring. what is the main purpose of a cover crop? a. to get rid of excess seed rather than storing during the winter b. to provide food and shelter for birds and animals during the winter c. to prevent water runoff into other parts of the farmers' field d. to prevent erosion of the topsoil by wind and water

Option (D)

Explanation:

A cover crop is usually defined as a special type of crop that is cultivated in order to increase the productivity of the soil, rather than focusing on the productivity of the crop. These are very commonly used and it helps in the decreasing amount of weeds, controlling pests and diseases, increasing the fertility of the soil, reduction of soil erosion. It also enhances the biodiversity.

Thus, the main purpose of the cover crop is to prevent the erosion of the topsoil by the agents such as water and wind.

Hence, the correct answer is option (D).

a.metals can become magnetic if they have many spinning electrons that create magnetic fields.d.only some metals are attracted by magnets; these metals are called ferromagnetic.

d.wrapping an insulated wire around a metal with ferromagnetic properties and applying an electric current.