When searching on YouTube for a theme-based collection of videos, which option would be most effective?

Filtering by playlist is the most effective option when searching for a theme-based collection of videos on YouTube. Playlists allow users to organize multiple videos that share a common theme, topic, or narrative. By focusing on playlists, you can access a curated set of videos that are linked together, making it easier to explore a subject comprehensively without having to sift through individual videos one by one.

Channels, while they may contain videos on similar topics, are generally broader and might include varying content types that aren't necessarily focused on a single theme. Filtering by upload date is useful for finding the most recent content but does not ensure that the videos are thematically connected. Filtering by view count could help identify popular videos, but it does not have any bearing on the content’s thematic relevance. Therefore, using playlists is the best approach to locate a cohesive set of videos centered around a particular theme.