A Physician Has Ordered the Measurement of a Cardiac Patient's

A physician has ordered the measurement of a cardiac patient's electrolyte levels as part of the client's morning blood work. Which of the following statements best captures the importance of potassium in the normal electrical function of the patient's heart?

A) Potassium catalyzes the metabolism of ATP, producing the gradient that results in electrical stimulation.
B) Potassium is central to establishing and maintaining the resting membrane potential of cardiac muscle cells.
C) The impermeability of cardiac cell membranes to potassium allows for action potentials achieved by the flow of sodium ions.
D) The reciprocal movement of one potassium ion for one sodium ion across the cell membrane results in the production of an action potential.