Answer: Option (b) is the correct answer.
Step-by-step explanation:
A gamma particle is basically a photon of electromagnetic radiation with a short wavelength.
Symbol of a gamma particle is
. Hence, charge on a gamma particle is also 0.
For example,

So, when a nucleus decays by gamma decay to a daughter nucleus then there will occur no change in the number of protons and neutrons of the parent atom but there will be loss of energy as a nuclear reaction has occurred.
Thus, we can conclude that the statement daughter nucleus has the same number of nucleons as the original nucleus., is correct about if a nucleus decays by gamma decay to a daughter nucleus.