The correct set of four quantum numbers for the valence electron of...

Electronic configuration of $Rb = \left[Kr\right]5{s}^{1}$

$Rb$ is alkali metal with valence electron in $5s$ subshell. Hence, $n = 5$

$Rb = [ Kr ] 5{s}^{1}$

$n = 5$

$l = 0$

$m = 0$

$s = + \dfrac{1}{2}$ or $- \dfrac{1}{2}$

Hence, the answer is option A,