The correct option is C Earthworms
Earthworms are the organisms which improve the texture of the soil by burrowing into the soil, making it loose and allowing the air to enter into it. They make the soil porous and also form tunnels or holes in the soil which allow the roots to spread through it and get more air and water. They are also known as friend of the farmers, as they help to increase the fertility of the soil by bringing the nutrients up from deep soil and depositing them on the surface.