What does a video frame comprise of?

A video frame is indeed comprised of a complete set of horizontal lines displayed at once, which is fundamental to how video is structured and viewed. Each frame represents a single snapshot in time of the moving image, capturing all the visual information that will be displayed at that moment.

This idea is rooted in the way video is constructed, typically using either interlacing (where alternate lines are drawn in successive fields) or progressive scanning (where all lines are drawn in each frame). In either case, the frame as a whole is defined by these horizontal lines that create the full picture, thus ensuring that the viewer receives a coherent image.

In contrast, a still image made up of alternating lines would not accurately represent the complete image necessary for video. Multiple fields shown simultaneously does not apply since fields are generally part of a larger frame, and a collection of independent still images refers to a format that does not create the fluid motion that video requires. Instead, frames work together in succession to convey movement and continuity in video content.