Which layer of soil often contains litter?

The question says,' which layer of soil often contains litter. The answer is O layer. A soil profile is a vertical section exposing layers of the soil horizons from the ground surface to the parent rock. The layers are represented by the letters, O, A,B, C, R. The O layer is the topmost layer and contains most of the soil humus and decomposed plant litter.

The answer to the question is c.