RE: "A."
Plants get energy from the sun (photosynthesis), but the production of Carbon Dioxide does not give any living thing the energy to perform their life processes.
RE: "B."
The Moon's reflective light does not give any living thing the energy to perform their life processes.
RE: "C." [Best answer]
The breakdown of food does give any living thing the energy to perform their life processes.
RE: "D." Plants' roots "fix" Nitrogen gas from the atmosphere, but that does not give any living thing the energy to perform their life processes.