In what situation can a caught fly ball be ruled a fair ball?

A caught fly ball is ruled a fair ball when it is caught in fair territory. This is fundamental to understanding how live ball regulations work in baseball. When a fly ball is hit and remains in fair territory, it is deemed a live ball and can be fielded by players. If the ball is caught while in fair territory, it results in an out for the batter.

In contrast, if a fly ball is caught in foul territory, it is ruled a foul ball, and the batter is not out unless they already have two strikes against them. The other options reflect scenarios that do not align with the rules governing fly balls. A ball that hits the ground first or is caught after bounces cannot be considered a caught fly ball and thus do not fit the criteria for being ruled fair.