If heat is consumed during a reaction, the reaction is said to be

If heat is consumed during a reaction, the reaction is said to be an endothermic reaction.
There are two types of reactions related to heat energy, these are endothermic and exothermic reactions. 
Exothermic reactions are when the reactions as it proceeds gives out heat energy  to the surroundings. Endothermic reactions are when heat energy is absorbed by the reactants to initiate and continue the reaction. Therefore reaction system absorbs or consumes heat energy from the surrounding.

It’s the energy source of stars

The answer is a) carbon-12