"Do you know the blue team players?"
Translation:Tu connais les joueurs de l'équipe bleue ?
The verb 'savoir' is used for facts and for knowing things. For example: "Je sais que ma chambre est plus grande que celle de ma mère" (I know that my bedroom is bigger than my mother's.)
The verb 'connaître' means 'to know' too but can also translate to 'to be familiar with.' You'd use this one when referring to knowing places or people. For example, "Je connais bien cet endroit" (I know this place well) or "Est-ce que vous connaissez Gilbert ?" (Do you know Gilbert?)
Here's a link to another thread that may help: https://forum.duolingo.com/comment/17631649/How-do-you-tell-the-difference-between-savoir-and-connaitre
I hope that helped :)
It's basically random. French has two words for "you", so the official correct response to every E to F translation has to be one of them. The other is always also accepted as long as the rest of the sentence is corrected.
Of course if the sentence is clearly a plural You then it's Vous.
Duo does seem to choose Tu when the sentence is likely to be said from one friend to another (like this one). And Vous when the sentence is likely to be said between strangers (like "Do you have your passport, madam?")