What causes a resting potential to develop in a neuron?
a. diffusion of sodium and potassium ions
b. active transport of sodium and potassium ions
c. active transport of sodium and diffusion of chloride ions
d. active transport of potassium and diffusion of chloride ions

The (a) resting membrane potential is a result of different concentrations of Na+ and K+ ions inside and outside the cell. A nerve impulse causes Na+ to enter the cell, resulting in (b) depolarization. At the peak action potential, K+ channels open and the cell becomes (c) hyperpolarized.