It would be d.
Reason being said...
the electron configuration normally goes like this...
1s2 2s2 2p6 3s2 3p6 4s2....
until you hit the transition metals..remember those have a special rule..
even though you are in the 4 sublevels for the orbitals ... it goes down 1
Making it 3d..(1,2,3,4,5,6,7,8,9,10)
Going on...
at 5s2 then, 4d1, 4d2, 4d3, 4d4, etc..
at 6s2 then, 5d1, 6d2, 6d3, 6d4, etc..
Thus, D orbital is your answer.
