What is true about an inductor concerning AC and DC signals?

The statement that an inductor opposes changes in current is accurate. Inductors are components that store energy in a magnetic field when an electric current flows through them. In direct current (DC) circuits, once the current reaches a steady state, the inductor behaves like a short circuit, allowing DC to pass without resistance after the initial change. However, when there is a change in current, such as when the circuit is turned on or off, the inductor generates a back electromotive force (back EMF) that opposes the change according to Lenz's Law.

In alternating current (AC) circuits, the current is constantly changing direction and magnitude. The inductor also reacts to these changes by opposing the current flow, resulting in a phase shift between voltage and current. This property is crucial in various applications, including filters and oscillators. Thus, the inductor's ability to oppose changes in current is fundamental to its functioning in both AC and DC environments.

The other options describe characteristics of inductors inaccurately or misleadingly.