What is the purpose of the "pump" motion in pitching?

The pump motion in pitching serves to prepare for the pitch delivery. This action is an integral part of a pitcher's mechanics as it helps to create momentum and set the stage for a more effective and powerful delivery. By going through this motion, the pitcher is able to achieve better timing and synchronization of their body movements before releasing the ball, which can lead to improved accuracy and velocity. Additionally, the pump motion can engage the pitcher's core and lower body, ultimately enhancing the overall effectiveness of the pitch.

Options that suggest the pump motion is intended to confuse the batter or to signal to base runners do not accurately reflect its primary function. While setting a rhythm can be impacted by the motion, it's more about establishing a physical readiness rather than establishing a rhythmic pattern for the batter's perception. Therefore, the primary purpose of the pump motion is indeed to prepare for the pitch delivery, making that the most appropriate choice.