Final answer:
The closure of sodium leak channels does not alter the resting membrane potential of -70 mV, suggesting that the potential remains stable, and it does not cause repolarization, depolarization, or hyperpolarization.
Step-by-step explanation:
When sodium leak channels close, the resting membrane potential remains at its value of -70 mV because the sodium channels are not the primary determinant of the resting potential; the potassium ions (K+) and their leakage channels play a more significant role in maintaining it. The closure of sodium channels does not lead to repolarization, depolarization, or hyperpolarization. The option that states the membrane potential 'returns to -70 mV' could be potentially misleading, as the closure of sodium leak channels does not alter the membrane potential if it is already at the resting level. Therefore, the most appropriate option in the context of the question is E) membrane stabilization, assuming that the membrane potential is at -70 mV to begin with.