A sign with a green background and white letters or numbers, visible from great distances, is positioned above or to the right of the highway. The arrows on the sign indicate the lane you should be in if you intend to exit the road. These signs are:

A. Primary Route Guide signs seen on Tennessee's Secondary Highway routes
B. Guide signs seen at the entrance of all tourist attractions, hospitals, and national parks
C. Guide signs seen on Tennessee's Interstate Highways

Signs with a green background and white letters on Tennessee highways are Guide signs for interstate highways, directing drivers to the correct lanes for exits. They are integral to the visual language that aids navigation and are part of the wider commercial language of signage in communities. So, the correct option is (C) Guide signs seen on Tennessee's Interstate Highways.

Explanation:

The signs with a green background, white letters, and numbers that are seen at great distances above or to the right of the highway, with arrows pointing to the lane you should be in if you intend to leave the road, are Guide signs seen on Tennessee's Interstate Highways. These signs are part of the visual language that guides drivers along their journeys, providing clear and concise information on directions and destinations. This visual language is not limited just to the roadways but also extends to highway billboards, store signs, and product advertisements that form a commercial language visible in the community.

These highway guide signs are critical in assisting motorists in navigating and understanding important geographic information, such as exits and services available at upcoming interchanges, much like how signage in a town or city can guide visitors to various destinations. Moreover, the use of familiar symbols, such as arrows and recognizable color schemes, ensures that the communication is effective and immediate, fulfilling the crucial role of signage in aiding both navigation and commercial communication.