At boxing practice, Nathan works with his coach to improve the strength of his punch. Nathan lost his balance when he hit the bag with a hard punch. He says that's because of the reaction force from his punch, which was large because the bag is heavy. Is he correct?

Answer Choices
A. Yes, he is correct
B. No, it is not the weight, it is the large mass of the bag that gives the large reaction force.
C. No, the reaction force depends on the force of Nathan's punch, not the mass of the bag.
D. No, the bag does not exert a reaction force, because it is flexible.