A batter is considered out in which situation?

A batter is considered out in several situations, each corresponding to specific rules in baseball. The first situation, when the ball is caught on the fly, is a fundamental rule where if a batted ball is caught before it touches the ground, the batter is deemed out. This rule promotes fair play and gives the fielding team an opportunity to make a defensive play.

The second scenario, where the batter swings and misses at a third strike, is another well-established rule. In baseball, a strikeout occurs when a batter fails to hit the ball after three strikes, and this can occur even if the third strike is not caught by the catcher, provided the ball is not deemed a foul.

The third situation, where the batter steps outside the batter's box, can also result in the batter being called out. This action is typically enforced under rules that emphasize the necessity for a batter to remain in the designated area while attempting to hit the ball.

Each of these situations reflects the rules governing batting in baseball, reinforcing the mechanics of the game and maintaining its structure. Therefore, the correct choice encompasses all these scenarios, as they each represent valid instances where a batter can be ruled out.