5f sublevel
n=5,
l = 3
n+l=8
number of possible orbitals = 7
this is because for f subshell, as l=3 there are 7 possible values of ml (-3,-2,-1,0,1,2,3) each ml value corresponds to an orbital
Maximum number of electrons = no. of orbitals * 2 = 14 (Pauli's exclusion principle: each orbital can accommodate a max of 2 electrons)
So, (b) and (d) are correct.