A. Decomposition is driven by internal energy.
There are many factor that conditionate the rate of decomposition, for example the physical environment (temperature, moisture and soil properties). But also, the microbial community of decomposers available and the quantity and quality of the organic material to be decomposed. As there are living organisms involved, and all the energy from living organsims, as even animals obtain energy indirectly from the sun through photosynthesis, it can be said that decomposition is driven by both types of energy.
