What does a red circle with a white horizontal line indicate?

Answer: C — No entry allowed

A red circle with a white horizontal line is a universal symbol indicating that entry is not allowed. This sign is typically placed at the entrance of a one-way street, a restricted area, or on roads where drivers are prohibited from entering an area for safety or legal reasons. It conveys a clear message to drivers that they must not proceed in that direction, ensuring safety and order on the road. In contrast, a speed limit sign typically features a number indicating the maximum allowable speed in that area, and a yielding sign would be more triangular in shape. A no left turn sign is specifically shaped and often also includes an arrow to show the direction that is restricted. Understanding these signs and their meanings is crucial for safe driving and compliance with traffic regulations.