Why is C wrong?

The video did not help, talking about how the answer is irrelevant just because does nothing to help

C doesn't actually give us anywhere near enough information. Effects can absolutely happen without one possible cause. Almost all effects are overdetermined. I could be wet because it rained, because it is hot out and I'm sweaty, because I went for a run, because I just got out of the pool, etc. the fact that the majority of people who are soaking wet did not just get out of the pool doesn't mean that swimming doesn't cause one to be wet. In this case it depends on the relative sizes of the population. We would want data about the percentages of smokers and non smokers who snore. C doesn't give us this,