by compacting the topsoil by decreasing the fertility of the topsoil by adding nutrients to the topsoil by removing the minerals from the topsoil
I am hesitating between 4 options to answer the following question, which option should I choose?
Question: Earthworms move randomly throughout topsoil. How do earthworms most likely affect the topsoil?
Possibilities:
- by compacting the topsoil
- by decreasing the fertility of the topsoil
- by adding nutrients to the topsoil
- by removing the minerals from the topsoil

by adding nutrients to the topsoil