Which of the following best describes a legal wind-up position for a pitcher?

A legal wind-up position for a pitcher is characterized by the specific placement of the feet relative to the pitching plate. The correct option indicates that the entire pivot foot must be on the pitching plate. This means that when a pitcher is in their wind-up, they need to ensure that their pivot foot, which is typically the back foot, is entirely planted on the pitching plate, providing stability and balance necessary for an effective pitching motion.

The reason this is crucial is that it establishes the pitcher's legal position prior to delivering the pitch. If the pivot foot is not on the plate, it can lead to various rule violations, such as balks or illegal pitches. This requirement ensures that the pitcher remains within the defined area to deliver their pitch legally and allows for a proper and controlled throwing motion.

The other options describe positions that either misplace the pivot foot or do not adhere to the specific requirements set forth in baseball regulations, leading to confusion about compliance with the regulations governing pitching. Maintaining the standard that the entire pivot foot must be on the pitching plate is essential for both the integrity of the game and the safety of all players involved.