What property of an alternating current circuit opposes changes in voltage?

The property of an alternating current circuit that opposes changes in voltage is inductance. Inductance occurs when there is a coil of wire (or inductor) in the circuit that generates a magnetic field when current flows through it. When the current changes, the magnetic field changes, which induces a voltage (often referred to as a back electromotive force or back EMF) that opposes the change in current. This phenomenon is described by Lenz's Law, which states that the direction of induced current will always be such that it opposes the change in magnetic field that produced it.

While capacitance and resistance play roles in AC circuits, they do not specifically oppose changes in voltage. Capacitance stores energy in an electric field and can oppose changes in current rather than voltage. Resistance dissipates energy in the form of heat and does not produce a reactive effect. Reactance, which encompasses both inductive and capacitive effects, is the total opposition to the flow of alternating current, but it is specifically inductance that is responsible for opposing changes in voltage through the mechanism of back EMF.