How are prohibitory signs typically displayed?

Answer: C — With a red circle and a red slash

Prohibitory signs are designed to indicate actions or behaviors that are not allowed, such as "No parking" or "No U-turn." The standard way to display these prohibitory signs is through the use of a red circle, which universally signifies restriction or prohibition. The addition of a red slash across the circle reinforces the message, clearly indicating that the specific action is prohibited. This design is effective because it captures the driver's attention and communicates the restriction quickly and unmistakably, ensuring that road users understand the rules they must follow. The use of red as a color also signifies warning or danger, further enhancing the visibility and importance of obeying the sign. Other sign configurations serve different purposes. For instance, signs with a blue circle typically indicate that a certain action is permitted, green squares often provide information or guidance, and yellow triangles warn of potential hazards. Therefore, these other options do not convey prohibitory messages and are not used for that purpose.