Answer: A) the sun
Explanation: Nuclear energy can be defined as the energy which is present in the core of an atom. The core contains large amounts of energy present in the bonds that hold the nucleus together.
In sun nuclear fusion takes place where two or more atoms combine to form a larger atom, and a huge amount of energy is released in the process.

Rocket engines and a coal burning power plant convert chemical energy stored in the bonds of chemicals to heat and light energy. In volcanoes heat energy of the magma is converted to light energy and the mechanical energy is converted to sound energy.