What is one characteristic of an Official Traffic Control Device?

Answer: C — It must be approved by a public body or officer

An official traffic control device must receive approval from a public body or officer to ensure that it meets established standards for safety and effectiveness. This requirement is in place to maintain consistency, compliance with national regulations, and to uphold public safety on roadways. The approval process typically involves evaluation against specific guidelines that govern design, placement, and functionality, helping to standardize how traffic control strategies are implemented within various jurisdictions. The other aspects mentioned, such as the ability for anyone to install these devices, their authority to enforce local laws, or the unrestricted nature of the messages they can convey, do not align with the structured regulatory framework that governs traffic control devices. These devices are critical tools in managing traffic flow and enhancing roadway safety, and as such, they must adhere to strict guidelines, ensuring their reliability and understanding among drivers and pedestrians alike.