The two pieces of evidence that would be most relevant to the claim "Some young people who may have once said they wanted to be movie stars or professional sports players now aspire to be YouTubers" are:
B. a quote from a young person about what it would be like to make a living from YouTube
F. two polls spaced twenty years apart that asked young people about their dream careers
These two options directly relate to the changing aspirations of young people regarding careers, providing both a personal perspective and historical context on shifts in career ambitions.