Many gardeners add earthworms to their soil if none are already living there. Why would gardeners do this?

A. Earthworms are useful to have when the gardener wants to go fishing.


B. Earthworms eat the roots of weeds, causing the weeds to die.

C. Earthworms release a chemical into the soil that acts as a natural pesticide.

D. Earthworms help to increase the fertility of soil.