Ultimately, Player A will win this pot unless Player B's cards didn't make it all the way to the muck pile. We have no way of knowing if Player B had a better hand or not. If you think it was deliberate, you need to penalize Player A.
12: Declarations. Cards Speak at Showdown
Cards speak to determine the winner. Verbal declarations of hand value are not binding at showdown. However, deliberately miscalling a hand may be penalized. Any player, in the hand or not, should speak up if he thinks a mistake is being made in the reading of hands.