The correct option is B 3
We know that,
values of l=0,1.....,(n−1)
where, n is principal quantum number and l is azimuthal quantum number
For third shell, n=3,
On putting n=3, we get,
i.e l = 0, 1, 2
we know,
No. of possible subshells = no. of possible values of l.
So, number of subshells = 3.