Which of the following output devices is used primarily for video display?

Television sets are primarily designed for video display, making them the most suitable choice among the options provided. They are equipped to render complex images and videos, displaying various formats of visual content for viewing. Television sets have advanced through technology to offer high-definition (HD) and even 4K video outputs, making them an ideal medium for watching video content.

Speakers, on the other hand, are audio output devices that produce sound rather than video. Microphones are input devices that capture sound and do not play any video at all. Keyboards are input devices used for typing and do not have the capability to display video or images. Therefore, television sets are uniquely suited for the function of displaying video, distinguishing them clearly from the other options listed.