What does it mean if you see a sign with a red circle and a slash through it?

Answer: C — The action is prohibited

A sign featuring a red circle with a slash through it clearly indicates that a certain action is prohibited. This type of sign is recognized as a universal symbol for "no" or "not allowed," which is used to inform drivers and pedestrians that they must refrain from engaging in the specified action. For instance, a sign depicting a red circle and a slash over a bicycle suggests that biking is not permitted in that area. This visual cue helps maintain safety and order on the roads by clearly communicating restrictions to all road users, ensuring they are aware of and adhere to regulations intended to prevent accidents and maintain traffic flow.