What must neither jumper do until the jump ball has been touched?

The requirement that neither jumper can leave the center-restraining circle until the jump ball has been touched is critical for maintaining the integrity of the jump ball process in basketball. This rule ensures that both players remain in their designated positions and do not gain any unfair advantage by moving out of the circle before the ball is tossed.

When the referee conducts the jump ball, their whistle signals the start of the play, and it is important that both jumpers adhere to the rules until that moment, ensuring a fair contest for possession of the ball. Leaving the center circle early could lead to an unfair advantage or an immediate violation, resulting in a turnover or another infraction.

This is why the other options do not capture the essential rule being addressed. Making any movement, looking at the referee’s signal, or jumping before the whistle introduce actions that may not necessarily align with the specific prohibition of leaving the circle itself, which is focused on the defined boundaries during the jump ball.