Consider a game in which player 1 moves first. the set of actions available to player 1 is a1={a,b,c}. after observing the choice of player 1, player 2 moves. the set of actions available to player 2 is a2={a,b,c,d}. at how many information sets does player 2 move?
since player 1 moves first, At the Time player-2 Only has 3 information sets to move at which means from player 1 's A ( player-2 can play a,b,c,d) , player-1's B ( player-2 can play a,b,c,d)and player-1's C ( player-2 can play a,b,c,d).