Which change takes place in a nuclear fusion reaction?

a) matter is converted to energy.
b) energy is converted to matter.
c) ionic bonds are converted to covalent bonds.
d) covalent bonds are converted to ionic bonds.

Matter is converted to energy.

Explanation:

In a chemical reaction we consider that matter is conserved.It means in a chemical reaction the amount of matter on the reactant side is equal to the amount of matter on the product side.

However in case of nuclear reaction the matter gets converted to energy and thus there is loss of matter. Due to this conversion of matter into energy high amount of energy is associated with the nuclear reactions.

There is no change of ionic bond to covalent or vice versa.