What is a distinguishing feature of Alternating Current (AC) compared to Direct Current (DC)?

The distinguishing feature of Alternating Current (AC) compared to Direct Current (DC) is that AC changes direction periodically. In AC systems, the flow of electric charge periodically reverses direction, which is a fundamental characteristic of this type of current. This alternating flow allows it to be transmitted over long distances more efficiently and is commonly used in residential and industrial power supply systems.

In contrast, Direct Current (DC) flows in a single direction consistently. This means that while DC is stable and can provide a constant voltage, it does not exhibit the periodic reversal inherent to AC. Additionally, the varying voltage characteristic mentioned in one of the options relates more to the adaptability of both types of current rather than being a specific distinguishing feature. Thus, the capacity for AC to change direction periodically makes it unique when compared to the steady, unidirectional flow of DC.