What is one of the conditions under which mopeds are prohibited from operating?

Answer: C — On highways

Mopeds are prohibited from operating on highways due to safety considerations. Highways are designed for higher-speed vehicles, and the speed capability of mopeds typically falls well below that of other vehicles on highways. This disparity creates significant risks not only for moped operators but also for other drivers. Since mopeds can struggle to keep pace with traffic and are less visible due to their smaller size, their presence on highways can lead to dangerous situations, such as increased chances of accidents or conflicts with faster-moving vehicles. Therefore, this restriction aims to help ensure the safety of both moped riders and other road users.