Question

Two players $X$ and $O$ play a game of "noughts and crosses" on a $3\times 3$ grid. The purpose of the game is for a player to get $3$ symbols belonging to the player in a straight line $($vertically, horizontally or diagonally$)$. Each player marks one symbol on his or her turn. After two moves $(1$ turn each$)$, the grid looks as follows with $X$ to play next.
Where should $X$ put his symbol next so thathe will always win this game finally regardlessof how well $O$ plays?

• A. Bottom row right corner
• B. Bottom row middle cell
• C. Middle row left most cell
• D. It is not possible to always ensure $X$ wins if $O$ plays carefully

Answer 1

The correct option is A Bottom row right corner

We can label the cells as follows:
If xx is put on the Cell GG (bottom row right comer).
Case-II-OO is put in Cell FF.
Then xx puts in Cell AA. Now OO will put either in Cell CC or in Cell DD. Then xx puts in the other one and xx wins.
Case IIII-OO puts it anywhere other than FF.
xx puts in Cell FF and wins.