What is one characteristic of direct current (DC)?

• A. The current changes direction periodically.
• B. The current flows in one direction only.
• C. The current has varying voltage levels.
• D. The current requires transformers for effective transmission.

Answer: (B)

Direct current (DC) is defined by the fact that it flows in one direction only. This characteristic distinguishes it from alternating current (AC), where the current periodically changes direction. In a DC circuit, the electrons move steadily in the same direction, which allows for stable and consistent voltage levels. This feature is particularly useful in applications such as battery-operated devices, where a stable power supply is essential. Other options provided in the question refer to properties of alternating current or the requirements for transmission, which do not apply to direct current.