Which of the following is not a cause of soil depletion?
a. conservation tillage
b. erosion
c. overtilling
d. deforestation

a chair, a bed, and a toothbrush

explanation:

i was told this before by a teacher, so yeah

i believe it is "they are not used up by reactions" as the answer to your question, text me back if this is correct because i just learned this.

answer; hydrologic cycle;