During an action potential, activation of voltage-gated sodium and potassium channels occurs at different rates. What is the effect of this difference on ion flow across an axon membrane?

At first there is no change in ion movement, then sodium ions flow out of the cell followed by potassium ions later.

K+ will flow into the cell first followed by Na+ flowing out of the cell.

Initially, Na+ flows into the cell followed by K+ flowing out of the cell.

First, sodium ions flow into the cell then potassium ions flow into the cell.