john is a farmer who wants to keep his soil as productive as possible. Which of these actions would help his achieve this goal?

Crop Rotation

Explanation:

When farmers plant pick their out seed they pick plants that compliment eacother

Example. farmers will plant corn one year and soybeans the next then corn again because corn puts the required mineralsin the soil for soybeans, and the soybeans put the needed minerals in the soil for corn to grow.

answer; i believe the correct answer is (a) nigeria is the largest african crude (oil) supplier; /// so revenue from petroleum;