Answer:

C. Decaying living things

Explanation:

The decomposition of organic matter in the soil creates humus, a material with a complicated chemical structure and a black hue due to the presence of carbon-rich molecules.

Answer:

B. More Water

Explanation:

Soil color is influenced by its mineral composition as well as water and organic contents. For example, soils high in calcium tend to be white, those high in iron reddish, and those high in humus dark brown to black. Soil needs only about 5% organic material to appear black when wet