# The atomic numbers of elements X,Y and Z are 19,21 and 25 respectively. The number of electrons present in the M shell of these elements follow the order:

$\begin {array} {1 1} (a)\;Z > X > Y & \quad (b)\;X > Y > Z \\ (c)\;Z > Y > X & \quad (d)\;Y > Z > X \end {array}$