What is the key purpose of using regulatory signs on the road?

The key purpose of using regulatory signs on the road is to indicate traffic laws. These signs serve as essential guides for drivers, informing them of the rules they must follow to ensure safe and orderly traffic flow. Regulatory signs often include speed limits, stop signs, yield signs, no parking signs, and other critical rules that govern driving behavior and road usage. By clearly communicating these regulations, these signs help maintain safety and reduce the likelihood of accidents.

Understanding the function of regulatory signs is crucial for drivers, as compliance with them is not optional; it is a legal requirement. This contrasts with the other types of signs mentioned in the options, which serve different purposes. For example, directional signs aid in navigation, warning signs alert drivers to potential hazards, and aesthetic signs may enhance the visual appeal of the road environment but do not convey critical driving information.