please explain im confused

Atomic \& Molecular Structure - Question Bank \#32 Difficulty Level: Medium Which of the following lists the subshells in order of increasing energy? A. 3s, 3p, 4s, 3d, 4p, 4d, 5s [8\%] B. 3s,3p,4s,3d,4p,5s,4d[72%] C. 3s,3p,3d,4s,4p,4d,5s [13\%] D. 3s,3p,3d,4s,4p,5s,4d[4%] E. 3s,3p,4s,3d,4d,4p,5s[3%]