In an Unstimulated Neuron, the Sodium-Potassium Pump Maintains the Concentration

In an unstimulated neuron, the sodium-potassium pump maintains the concentration gradient of sodium and potassium ions by transporting

A) potassium ions into and sodium ions out of the cell.
B) potassium ions out of and sodium ions into the cell.
C) sodium and potassium out of the cell.
D) sodium and potassium into the cell.
E) sodium and potassium ions in both directions across the cell membrane.