Multi-select: Knowing that "crop rotation renews soil", how would one answer "What is an example of the fact that crop rotation renews the soil?"

Select from:
-planting rows of carrots and peas next to one another.
-planting peas one season then carrots the next.
-planting a field of corn with different types in it.
-tilling the soil in between crops....A:
planting peas one season then carrots the next