The factors that affect soil formation are climate, rock type, slope, time, and biological activity. Differences in these factors will produce different types of soil. Soil type determines what can grow in a region. Humus, the decayed remains of living organisms, is essential for soils to be fertile.
The correct answer would be D) decomposers. Decomposers do just what they're named for. Decompose things. They break down dead plant and animal material, gaining nutrients from it, while releasing CO2 into the atmosphere.
