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Party members Alex, Bart, and Caroline are in combat with a Drow, in that turn order (A, B, C, D).
Alex uses the help action on the Drow, being within 5ft. If Bart chooses not to attack on her turn, can Caroline attack with advantage because of Help? If Bart decided to attack, would Bart have gotten advantage instead?
Does a specific ally need to be named to benefit from the advantage? Or is it first-to-attack?