The correct option is A 1
N has Z=7: 1s2,2s22p3, so 5e in the outer shell , 1 pair(of 2e, from 2s2) and 3 unpaired electrons.
O has Z=8: 1s2,2s22p4 so 6e in the outer shell. 2 pairs and 2 unpaired ones (ready to form 2 bonds to achieve stability). There are 3 orbitals p, px,py and pz. You have to first complete each one of them with 1e and if any electrons left, you pair them starting again from px, until you fill the orbital up. So, in O case,4e go like this:2e in px, 1e in py and 1e in pz. This is why you have 2 unpaired e for O.
Al has Z=13 : 1s2,2s22p6,3s23p1 so 3e in the outer shell, 3 unpaired electrons (1e in each of the px, respectively py and pz)