What must a player do if their ball moves during the backswing?

When a player's ball moves during the backswing, the correct procedure is to play the ball as it lies. This rule is outlined in the Official Rules of Golf, specifically concerning the actions of a player when their club is in motion. According to these rules, if a player has not yet taken a swing and the ball moves solely due to their taking the stance or preparing for the next shot, they are allowed to play it from wherever it ends up.

This provides clarity and a precise procedure for the player, ensuring that they do not incur unnecessary penalties when a minor movement of the ball occurs, which is common on the course. It emphasizes the pace of play and the natural conditions of the game, as the player is required to adapt to the situation at hand without disruption.

The other options do not align with the guidelines set forth in the Rules of Golf. For instance, repositioning the ball without penalty would not be applicable if the movement was not a result of an act of the player. Furthermore, calling for a ruling would generally not be necessary in standard situations of the ball moving during a backswing unless there were specific complexities involved.