Concept:Compost supplies humus, which is organic matter that helps soil retain moisture.
Explanation:Compost is made from fully decomposed plant and animal materials.
When mixed into soil, it raises the humus content of the soil.
Humus has very small pores and behaves like a sponge.
These pores trap water and release it slowly to plant roots.
As a result, compost increases the amount of water that the soil can hold.
It may also improve soil texture, but its most important benefit is boosting water-holding capacity.
Answer:C. increases water-holding capacity of the soil