Microorganisms have a major role in maintaining soil biodiversity. They recycle nutrients in ecosystems and decompose organic matter in soil. Organic matter contains dead and living plant and animal materials. Microorganisms convert these materials into simpler compounds that maintain soil quality and help with plant growth.

Which solution could best help to restore or increase microorganisms and soil biodiversity?
A.
adding manure or compost to the soil
B.
spraying chemical weed-killers and fertilizers on the soil
C.
removing all ground-covering plants from the soil
D.
adding sewage containing synthetic materials to the soil