Which of the following description about neuron action potential is correct?
选项：

A:A large amount of Na+ outflow makes a positive potential outside the membrane and a negative potential inside the membrane;
B:The concentration of Na+ in the cell is higher than that outside of the cell;
C:When the cells are stimulated and excited, Na+ channels open to cause Na+ outflow;
D:The Na+ channel is inactivated, the K+ channel is further opened, and the action potential naturally drops.