"Which of the following statements about voltage-gated channel proteins is true?A)If the membrane voltage reaches threshold potential, ions are pumped through the membrane.B)If the membrane voltage reaches threshold potential, ions can diffuse through the membrane.C)Ions can move through the membrane only if the overall membrane voltage stays the same.D)Ions are pumped through the membrane in order to maintain existing membrane voltage.E)When the gates close, membrane voltage does not change"

Voltage gated protein are sub unit of complex protein, they are transmembrane protein that forms Ion channels that are activated near the channel by a change in electrical membrane potential. The membrane potential regulates the closing and opening of this protein.

Cell membrane are not permeable to Ions, they being diffuse by transmembrane protein into Ions.

Hence, if the membrane voltage reaches threesome they can Ions can diffuse through the membrane because the cell are not permeable.