My sister _____ as a secretary in her company for three years and now she _____ to the manager of the sales department.

A．served; has been promoted

B．had served; has been promoted

C．has served; has promoted

D．was serving; has promoted

某元素原子3d轨道上有5个电子，则该原子最外层电子的排布可能是（　　）

A．4s¹

B．4s²4p¹

C．4s²4p³

D．3s²3p⁶3d⁵