Which of the following is not a possible cause of erosion?
a. burrowing animals
b. gravity
c. water
d. none of the above select the best answer from the choices provided

The correct answer is; d. none of the above  

Erosion is a process in which there is gradual wearing away of the earth surface by the action of natural elements such as water, wind, glacial ice and gravity. Burrowing animals, gravity and water are all possible cause of erosion. Burrowing animals are animals that create a hole or tunnel in the ground to provide suitable habitat or a byproduct of movement. The foot of hard-footed animals such as cattle and horses can create hole in the ground when the animals are walking. This makes the soil to become soft. Water or wind can erode the soil by transporting it to another location.

the correct answer is c.