Calculate the total number of electrons for n = 3, l = 2 and m = - 2

The total number of electrons for n = 3, l = 2 and m = - 2 is 10.

You might infer from this that the d subshell, indicated by the symbol l = 2, contains a total of 5 orbitals.
You can claim that you have two electrons because each orbital can only accommodate a maximum of two, one with spin-up and the other with spin-down. 

$\mathrm{L} = \frac{5 * 2\mathrm{e}}{1}$ 

L = 10e

As a result, in an atom, a maximum of 10 electrons can share these two quantum numbers.
$n=3,l=2$ ,these electrons are found in the 3d subshell, which is on the third energy level.

Hence, option C is correct.