Consider a Version of the Ultimatum Game in Which Player

Consider a version of the ultimatum game in which player 1 makes an integer offer {1,2 …,9} to player 2.If player 2 accepts,he or she gets that amount of money and 1 gets to keep the remainder of $10.If 2 rejects,both get nothing.Which of the following is an offer that arises in a subgame-perfect equilibrium assuming players only care about monetary payoffs?

A) 1.
B) 2.
C) 4.
D) 5.