What is the umpire's ruling when B1 hits a ball while any part of either foot is touching outside the lines of the batter's box?

When a batter, referred to here as B1, makes contact with the ball while any part of their foot is touching outside the lines of the batter's box, the ruling is that B1 is out for illegal contact with the ball. This rule is designed to ensure that the batter maintains a proper position within the confines of the batter's box during the act of hitting.

The batter's box is a designated area that provides a safe zone for the batter and contributes to fair play by ensuring that they have adequate space to swing without interference. Contact made outside this defined area can indicate a violation, which results in the batter being called out. This decision reinforces the importance of adherence to the specific rules regarding the batter's position prior to and during the swing, ensuring that all players are following the established guidelines for fair competition.

In contrast, the other options imply scenarios that do not align with the established rules regarding illegal contact. The options suggesting that B1 is allowed to run to first base or that a foul ball is called do not apply, as the illegal contact takes precedence. The option about no penalty being assessed also does not hold, as the action does incur a penalty in the form of an out.