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 pump moves sodium into the cell.
C) Depolarization causes voltage-gated sodium ion channels to open.
D) Sodium ion channels are opened by high extracellular calcium levels.
E) The opening and closing of ligand-gated channels cause depolarization.