Final answer:
Work zone signs on a highway provide directions, routes, and distances to drivers.
Step-by-step explanation:
On a highway, signs with black letters on an orange background provide: a.) directions, routes, and distances. These signs are known as work zone signs and are used to guide drivers through construction or maintenance zones by providing information about detours, lane closures, and other temporary changes to the road. They help drivers navigate the area safely and efficiently.