The fuel that releases carbon dioxide into the environment is the one that has carbon in its structure. Carbon reacts with oxygen to form CO2. One of the fuels used is biomass. Biomass has a carbonaceous structure that releases heat and CO2 when burned.
The other options are non-combustion energy. The solar harnesses the energy of the sun, the geothermal harnesses the energy of the interior of the earth and the nuclear harnesses the energy of the fission and fusion reactions of atoms.
Answer: A. Biomass