If B1 hits the ball and it strikes him outside the batter's box, what is the outcome?

When a batter, in this case B1, hits the ball and it strikes him while he is outside the batter's box, the play is ruled as a hit by pitch rather than a foul ball or any other outcome. However, if the batter intentionally strikes the ball and makes contact while outside the batter's box, the rule applies that the batter is automatically out. This is because the rules of baseball state that a batter must be in a proper position in the batter's box when attempting to hit the ball. If the batter is positioned incorrectly and still makes contact, the action is deemed illegal, resulting in the batter being called out.

The other choices don't apply in this situation: declaring the ball a foul is incorrect because the ball was not pitched; allowing play to continue normally overlooks the illegality of the action; and the advancement of runners does not occur as the batter's action invalidates his participation. Therefore, B1's situation directly leads to him being called out.