Which of the Following Situations Occurs in Electrically Excitable Cells

Multiple Choice

Which of the following situations occurs in electrically excitable cells?

A) When Na+ ion channels open,K+ ion channels close.
B) The sodium-potassium exchange pump moves sodium into the cell.
C) Depolarization causes voltage-gated sodium ion channels to open.
D) Ligand-gated sodium ion channels are opened by high extracellular calcium levels.
E) Proteins tend to diffuse out of the cell.