Let a number in each square as shown indicate the location of a mark. Then, from [3], the seventh mark must be placed in square 5 and, from [2], the seventh mark wins for both X and O. So the sixth mark must have been placed in a line already containing two of the opponent’s marks in either square 7 or square 9; otherwise, either X or O would have been placed in square 5. But, from [3], the sixth mark could not hve been placed in square 7 because square 5 would have been the required location for the O in square 7. So the sixth mark 2as placed square 9 and was X. Then, from [1], the seventh mark will be O and, from [2], O wins the game. From previous reasoning, the fifth mark placed in the game can also be determined: O is square 8.