The correct interpretation of how the authors of "YouTube" and "TikTok" see the popularity of TikTok among young people is:
A. The author of "TikTok" believes it suggests young people enjoy watching TikTok videos of various lengths, while the author of "YouTube" believes it suggests young people like knowing what kinds of videos they will likely see.
This reflects a difference in perspective on what the popularity of TikTok indicates about the preferences and behaviors of young viewers compared to that of YouTube.