Concept:Road signs are visual devices placed on roads to inform, guide, and protect all road users.
Explanation:Road signs mainly communicate important rules, warnings, and directions to road users.
They do not exist only to correct road users or help police arrest defaulters.
They are not limited to guiding police command traffic.
Instead, their primary purpose is precautionary: to prevent confusion, reduce accidents, and ensure safe movement on roads.
Therefore, they serve as precautionary devices that guide every road user.
Answer:D. precautionary devices to guide road users.