What defines a legal pitch in baseball?

A legal pitch in baseball is defined by specific criteria that govern how the pitch is delivered. One of these criteria is that the ball must pass through the strike zone, which is the area over home plate and between the batter's knees and the midpoint of their torso when they are in a standard batting position. This ensures that the pitch can be considered as either a strike or a ball, depending on the batter's response.

Additionally, for a pitch to be legal, the pitcher must remain on the pitcher's mound during the delivery. The pitcher's position is crucial as it ensures the proper execution of the motion required by the rules. If the pitcher steps off the mound or delivers the pitch from an invalid position, it could be ruled illegal.

Thus, both the requirement for the ball to pass through the strike zone and the necessity for the pitcher to stay on the mound contribute to defining a legal pitch. Therefore, the correct answer acknowledges that both conditions must be met for a pitch to be deemed legal in baseball.