What is the ruling if B1 hits a ball that strikes him while in the batter's box?

When a batter, in this case B1, hits a ball that then strikes him while he is still in the batter's box, the correct ruling is that the ball is declared a foul ball. According to the rules, if a ball is hit and subsequently strikes the batter before either reaching the catcher or the ground, it is treated as a foul ball.

This ruling serves to protect the integrity of the play, as the batter's box is a designated area where certain interactions between the batter and the ball are governed by specific rules. The foul ball declaration also retains the count of strikes or balls the batter had prior to the incident, ensuring that the at-bat continues without penalty to the batter. Therefore, it's essential for players and coaches to understand this situation to maintain consistency in gameplay.