The correct option is D M(N,Z)=NMn+ZMp−B/c2
Mass defect Δm=Bc2
Also,
Mass defect = Total Mass of protons + Total Mass of neutrons - Mass of the nucleus
⇒ Mass of the nucleus = Total Mass of protons + Total Mass of neutrons - Mass defect.
⇒M(N,Z)=NMn+ZMp−Bc2
Hence, the option (D) is correct.