The given reaction is a fusion reaction.
Answer: Option B
Explanation:
A nuclear fusion reaction is the one where two atoms are made to collide with each other and they will combine to form a heavier atom. In this reaction, a deuterium atom is made to collide with a tritium atom and lead to formation of helium atom with the release of a neutron.
So, the energy required to combine these two isotopes of hydrogen will lead to form a heavier element named helium. This is one of the basic reaction in fusion reaction, fulfilling all the selection criteria for the fusion reaction.