What characterizes alternating current (AC)?

Alternating current (AC) is characterized by its ability to reverse its direction continuously. This means that the flow of electric charge changes periodically, oscillating back and forth rather than flowing steadily in one direction. This fundamental quality of AC is what allows it to be efficiently transmitted over long distances and is a key reason why it is the predominant form of electrical energy used in homes and businesses.

In contrast to the other options, which do not accurately represent the nature of AC, it's important to note that AC is not confined to a single direction of flow; therefore, the idea of it flowing in one consistent direction only is inaccurate. Furthermore, while the strength of AC can vary based on its source and usage, it cannot be deemed consistently strong and constant, as there are many factors influencing its amplitude and power levels. Additionally, AC is commonly used in various applications, including electrolysis, making the claim that it cannot be used for such processes incorrect. Thus, the hallmark of AC—its continuous directional reversal—makes option B the correct assertion.