If the principal quantum number $n=6$, the correct sequence of filling of electrons will be :

Question

$\begin{array}{1 1} ns \to n \rho \to (n-1) \to (n-2) f \\ ns \to (n-2) f \to (n-1) d \to np \\ ns \to (n-1) d \to (n-2) f \to np \\ ns \to (n-2) f \to np \to (n-1)d \end{array}$