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 that he will always win this game finally regardless of 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

In the given figure, if X puts his cross on the bottom right corner or the top left corner he'll be stopping O from making a line vertically or horizontally according to the side he chooses. Then O will be focused on blocking the completing line of X either vertically or horizontally by putting an o in the middle of the two x. In the other turn x can put an x on the other box he chose the first time and he'll prevent O from winning and win the game at the end as he'll be able to get a chance on completion of lines horizontally and diagonally in a single chance. O can only block one line but the completion of the other will ensure X's victory.

Option A is the correct answer.