Answer: Option (c) is the correct answer.
Step-by-step explanation:
A reaction in which there occurs change in the number of protons or neutrons because of collisions between two nuclei or an atom and a subatomic particle is known as a nuclear reaction.
For example,

Here, a neutron is added to the nucleus of hydrogen atom. Therefore, it is a nuclear reaction.
In a chemical reaction there is gain or loss of electrons which results in the formation of a new compound and no change in the nucleus of an atom.
Thus, we can conclude that the given reaction is classified as a nuclear reaction rather than a chemical reaction because a change has occurred in a nucleus.