Which shows the sub-levels in order of increasing energy in the fourth energy level of an atom?

A.     \({\text{f}} < {\text{d}} < {\text{p}} < {\text{s}}\)

B.     \({\text{p}} < {\text{d}} < {\text{f}} < {\text{s}}\)

C.     \({\text{d}} < {\text{f}} < {\text{p}} < {\text{s}}\)

D.     \({\text{s}} < {\text{p}} < {\text{d}} < {\text{f}}\)

D