At what point does a jump ball become live?

A jump ball becomes live at the moment the ball is legally tapped by one of the jumpers. This is an important aspect of the game, as it signifies the beginning of play and the competition between the two players who are vying for control of the ball. The legality of the tap encompasses things like the jumpers having both feet in the jump circle and making a legitimate attempt to gain possession.

The other options don't mark the exact moment that play is initiated. For instance, the referee signaling for the jump ball is a necessary procedural step, but it does not itself make the ball live. Similarly, the ball reaching the center of the court or being thrown into the air are moments that occur as part of the process, but neither definitively defines when the jump ball is "live" for game play purposes. The key takeaway is that the moment the ball is legally tapped is what activates play and leads to the game's flow.