What sign indicates that a driver should not exceed the speed limit?

Answer: C — Speed limit sign

The speed limit sign is specifically designed to inform drivers of the maximum speed that is legally permitted on that stretch of roadway. It serves as a regulatory sign, meaning that it imposes a legal obligation for drivers to adhere to the indicated speed limit. Exceeding this limit can result in penalties or fines, as it is considered a violation of traffic laws. In contrast, yield signs and stop signs serve different purposes; yield signs instruct drivers to give way to other vehicles or pedestrians, while stop signs require drivers to come to a complete stop before proceeding. Warning signs indicate potential hazards or changes in road conditions but do not regulate speed directly. Therefore, the speed limit sign is the only sign amongst the options that specifically indicates a maximum speed limit that drivers must follow.