Microorganisms living in the soil form a major component of soil biodiversity. They play an important role in recycling nutrients in ecosystems by decomposing soil organic matter (SOM), which contains dead and living plant and animal materials. They convert these materials into simpler compounds that are important for maintaining soil quality and sustaining plant growth. Various agricultural practices such as crop rotation, tillage, fumigation, and use of pesticides and fertilizers affect the microbial biodiversity in the soil. Which solution could best be implemented to restore or increase soil microbe biodiversity in a particular area? A. Eliminate all cover crops from the soil. B. Spray weed-killing pesticides and chemical fertilizers on the soil. C. Add manure or compost to the soil. D. Add sewage sludge containing heavy metals to the soil.