Which of these accurately describes a difference between nuclear energy and fossil fuel?

The answer for the above question is, the nuclear energy has a higher energy density than fossil fuels. Nuclear energy is a quantity of energy measured in joules, therefore it has the same units as electrical and mechanical energy. It is the energy released during nuclear reactions, that is nuclear fission or nuclear fusion. Fossil fuel is a form of fuel that results from natural processes such as decomposition of buried organisms; it include coal, petroleum, natural gas, or crude oil.