Why Do Na+ Ions Enter the Cell When Voltage-Gated Na

Why do Na+ ions enter the cell when voltage-gated Na+ channels are opened in neurons?

A) because the Na+ concentration is much lower outside the cell than it is inside
B) because the Na+ ions are attracted to the negatively charged interior
C) because the Na+ ions are actively transported by the sodium-potassium pump into the cell
D) because the Na+ concentration is much higher outside the cell than it is inside, and the Na+ ions are attracted to the negatively charged interior
E) because the Na+ concentration is much higher outside the cell than it is inside, and the Na+ ions are actively transported by the sodium-potassium pump into the cell