Which set of the three quantum numbers (n, l, ml) corresponds to a 3d orbital?
n is the principle quantum number. It is the number that governs all the other quantum numbers. It limits l: l < n. and
Fortunately, it is given to you: 3d tells you that n = 3 for this set of orbitals.
l is the angular momentum quantum number. One way you can look at it is that l is the number of nodes (points of zero density) in the electron wave function. For l =0, there are no nodes os you get one big (for certain values of big) spherical orbital: an s orbital! for l = 1, you get orbitals with two lobes and a node centered at the nucleus. that is the description of a p orbital! for l =2, you get two nodes. For example, the