What if the players move sequentially? Say Alpha moves first. Here is a game tree that describes the situation. What is the Subgame Perfect Equilibrium (SPNE) in this game? Specify each players strategy properly.

4, 4 A Beta C 10, 0 A 16, -12 0, 10 B A Beta Alpha 9,9 C 18, 0 -12, 16 Beta A 0, 18 12, 12