What is a clean energy source that is an alternative to fossil fuels?

a. atomic energy

c. petroleum energy

b. gravitational energy

d. carbonization energy

The correct answer is (a) Atomic energy.

Atomic energy can be an alternative to the fossil fuels energy, protons and neutron are tightly packed inside the nucleus, they contain huge amount of energy, if we can break the binding force of the nucleus in an radioactive element so that it can propagate the chain reaction than we get energy tremendous amount, also it is an clean source of energy as it is not an hydro-carbon fuel.