More complicated versions of decision trees are used in all kinds of applications. That's what AIs use to win at tic-tac-toe or chess.

Which of these decisions would lead to a winning game for X?

B.A.

Exactly! AIs use similar methods to make decisions all the time.

If you haven't played tic-tac-toe in a while, that's ok. The AI wins if it adds X in the top right, so decision B.