Final answer:
The resting membrane potential of a cell is primarily influenced by its selective permeability to potassium ions (K+) due to more potassium leakage channels allowing K+ to move out of the cell, creating a negative charge inside the cell.
Step-by-step explanation:
The primary factor that influences the resting membrane potential of a neuron at rest is its selective permeability to potassium ions (K+). The resting membrane potential is approximately -70 millivolts, with the inside of the cell being more negative compared to the outside. This is due to the fact that the cell membrane has more potassium leakage channels than sodium channels, allowing potassium ions to move out of the cell more freely. As a result, a negative charge is established inside the cell because the loss of potassium ions exceeds the influx of sodium ions. Moreover, the sodium-potassium pump actively transports potassium ions into the cell while exporting sodium ions out, enforcing the difference in ion concentration across the cell membrane and contributing to the potential.
The answer to the question of what primarily influences the resting membrane potential of a cell is therefore: b) Selective permeability to potassium ions (K+).