How Do Sodium-Potassium Pumps Work

How do sodium-potassium pumps work?

A) sodium is pumped into the cell and potassium diffuses out
B) sodium is pumped out of the cell and potassium diffuses in
C) sodium and potassium are both pumped into the cell simultaneously
D) sodium and potassium are both pumped out of the cell simultaneously
E) sodium only binds to the pump to make it receptive to potassium which then is pumped into the cell