31. 一原子中之某一電子的四個量子數如下，請問何種狀態能量最低？(其中 n 為主量子數；l為角量子數；ml 為磁量子數；ms 為旋量子數)
(A) n = 4; l = 0; ml = 0; ms = 1/2
(B) n = 3; l = 2; ml = 1; ms = 1/2
(C) n = 3; l = 2; ml = -2; ms = -1/2
(D) n = 3; l = 1; ml = 1; ms = -1/2