Final answer:
High-definition (HD) represents the highest level of cable video services, offering sharper and more detailed image quality compared to standard definition.
Step-by-step explanation:
The highest level of cable video services is High-definition, represented by the abbreviation HD. High-definition refers to the quality of the video signal, which provides a sharper and more detailed image compared to standard definition. HD channels typically have a resolution of 720p or 1080i, while some newer channels may offer even higher resolutions like 4K. This higher level of quality requires more bandwidth and is often offered as a premium service by cable providers.