Final answer:
The term referring to the intermittent, spontaneous generation of action potentials is autorhythmicity, which is a characteristic of cardiac muscle meaning Rhythmicity (A). This results from spontaneous depolarization of autorhythmic cells in the heart.
Step-by-step explanation:
The intermittent, spontaneous generation of action potentials referred to in the question is known as autorhythmicity. This phenomenon is a key characteristic of cardiac muscle, which has the unique ability to initiate its own electrical impulses without external nervous or endocrine control. Autorhythmic cells in the heart undergo spontaneous depolarization, also called prepotential depolarization, where the membrane potential gradually increases due to the influx of sodium ions through open sodium ion channels. These spontaneous depolarizations trigger action potentials, leading to cardiac muscle contraction and establishing the heart's rhythm.
The correct answer to the question is A. Rhythmicity, which refers to the natural pacemaking capability of certain cardiac cells that generate rhythmic action potentials. This property allows the heart to maintain a constant heartbeat. The options B (Relative refractory), C (Antiarrhythmics), and D (Repolarization) do not correctly describe the intermittent, spontaneous generation of action potentials.