Answer: Option C
:
C
Temperature is a major factor that can affect the rate of decomposition. Decomposers are very active in soils having a temperature of more than 25 °C, with good moisture and aeration. Similar conditions prevail in the soil of tropical regions which marks the presence of a thick humus layer in these forests. However, under comparatively low temperatures, rate of decomposition is quite slow even if you have good moisture and aeration, indicating that temperature plays the determining role here.
Decomposition is also an oxygen dependent process. In the presence of oxygen, complex carbon compounds are oxidized to produce carbon dioxide. In this sense, decomposition is essentially equivalent to respiration. If oxygen is absent or in scarce supply, specialized bacteria decompose organic matter anaerobically. Anaerobic decomposition involves more chemical steps and is slower than aerobic. Thus presence of oxygen or aerobic conditions is also a major factor affecting decomposition.