In an experiment, an extracellular potassium concentration was increased until it became equal to the intracellular potassium concentration, which resulted in the loss of cellular excitability. What electrophysiological process occurred in this case?

Answer options

1. Potassium efflux from the cell decreases and hyperpolarization develops
2. Potassium efflux from the cell stops and resting potential disappears
3. Sodium efflux from the cell increases and depolarization develops
4. Potassium influx to the cell increases and local response develops
5. Potassium efflux from the cell increases and hyperpolarization develops