Which type of signs instruct road users to meet certain rule requirements or road conditions?

Regulatory signs are specifically designed to instruct road users about the rules and regulations that govern their behavior on the road. These signs dictate certain actions that must be followed, such as speed limits, must-stop or yield conditions, and lane usage. Their primary function is to ensure safety and compliance with traffic laws, which is crucial for the orderly flow of vehicles and pedestrians.

In contrast, warning signs serve to alert drivers to potential hazards or changes in road conditions ahead, while informational signs provide guidance to road users about locations, directions, and services available. Special instruction signs, as described in the context of your question, are not a recognized standard category in traffic control devices. Thus, the most accurate categorization for signs that enforce rules or requirements is regulatory signs.