Correct Option: A

Energy generated by using wind, tides, solar, geothermal heat, and biomass including farm and animal waste as well as human excreta is known as non-conventional energy. All these sources are renewable or inexhaustible and do not cause environmental pollution. More over they do not require heavy expenditure. Nuclear energy usually means the part of the energy of an atomic nucleus, which can be released by fusion or fission or radioactive decay.