Which of the following is responsible for the repolarization of the membrane after the peak of the action potential?

A)The membrane potential reaches the Na⁺ equilibrium potential.
B)The voltage-gated Na⁺ channels begin to inactivate.
C)The slowly opening voltage-gated K⁺ channels allow K⁺ to enter.
D)The influx of Na⁺ and the outflow of K⁺ are equal.
E)There is no longer a gradient to drive K⁺ out of the cell.