Explanation

(d)
The values of quantum number will give idea about the last subshell of element. From that value we can find the atomic number of element, $n = 3$ means 3rd-shell
$\begin{matrix}
l = 0 \\
m = 0
\end{matrix}\}$means subshell
It means it is 3$s$-subshell which can have 1 or 2 electrons.
∴ Configuration of element is
$1s^{2},2s^{2},2p^{6},3s^{1 - 2}$
∴ Atomic $i.e$., number is 11 or 12.