What happens if an umpire does not declare an infield fly when it could have been caught?

In the scenario where an umpire fails to declare an infield fly when one could have been caught, the rules dictate that the play is treated differently than a normal play. An infield fly rule is designed to prevent defensive players from intentionally dropping a catchable ball to create a double play by tricking the runners. If the conditions for the infield fly are present—specifically, there are fewer than two outs and runners on first and second (or bases loaded)—the umpire's failure to declare the infield fly does not negate the intended effect of the rule.

In this case, the situation indeed still dictates that the batter is automatically out due to the infield fly rule being applicable, despite the lack of an official declaration. This aims to protect runners from the risk of being caught off base due to the team's strategy. Thus, the outcome remains that the batter is considered out, which aligns with the enforcement of the infield fly rule's intent, ensuring fairness in gameplay.

The other choices incorrectly interpret the ramifications of the umpire's inaction and do not adhere to the established rules governing this specific situation.