When B2 steps out of the batter’s box, but F1 throws a pitch, what result occurs?

When B2 steps out of the batter’s box and F1 throws a pitch, the correct outcome is that the pitch is declared a no-pitch. This is because the batter must be in the box for the pitch to be considered a legal pitch. If a batter leaves the batter's box before the pitch is delivered, it does not count against the batter's count, and no strikes or balls are added. The rules require that the batter be in position to receive the pitch for it to be valid, thus the pitch thrown while B2 is out of the box is rendered invalid.