If M ( A;Z), $M_p\: and \: M_n$ denote the masses of the nucleus $ ^A_ZX,$ proton and neutron respectively in units of $u\: (1u=931.5Mev/C^2)$ and BE represents its bonding energy in MeV, then :

Question

$\begin {array} {1 1} (1)\;M(A,Z)=ZM_p+(A-Z)M_n+BE/C^2 & \quad (2)\;M(A,Z)=ZM_p+(A-Z)M_n-BE/C^2 \\ (3)\;M(A,Z)=ZM_p+(A-Z)M_n+BE & \quad (4)\;M(A,Z)=ZM_p+(A-Z)M_n-BE \end {array}$