Answer:
A. Total number of protons and neutrons
Step-by-step explanation:
In both nuclear reactions and chemical reactions, the total number of protons and neutrons are conserved.
It implies that the starting number of protons and neutrons in both reactions must be the same.
Chemical reactions involves, loss, gain or sharing electrons between two atoms.
Nuclear reactions deals with the nucleus of an atom.
It must be ensured that the mass and atomic number in nuclear reactions is conserved.