You would use vous, since M. Bernard means Mr. Bernard, and is formal. Generally if you're addressing someone as "Mme." "M." or "Mlle.", it's formal.
<em>Bonjour ! </em>
Boris : Alors, Cathy ! Comment ça va au lycée ? Il est important que tu "étudies" sérieusement, tu sais.
Vrai that is the answer because she won’t watch the sunset
Just search it up thats what i would do
