What must occur between the additional backward rotation and the pi rotation(s)?

The correct choice highlights the importance of maintaining proper technique and flow in synchro skating. After performing the additional backward rotation, it is essential for skaters to change feet before executing the pi rotations. This foot change allows for a smooth transition, ensuring that skaters can maintain balance and control as they shift directions.

In synchro skating, transitions are crucial for well-coordinated movements, and changing feet after backward rotations facilitates a seamless continuation of the routine. It also ensures that the skaters are aligned correctly for the upcoming movement, which contributes to the overall aesthetic and technical quality of the performance.

Other options, while they may relate to skating in different contexts, do not specifically address the necessary technical transition between these elements. For example, increasing speed without the foot change could disrupt the balance required for precision. Similarly, pausing would break the flow of the performance, and executing a jump may not logically connect with the requirements of transitioning into pi rotations. Therefore, changing feet is a crucial step that supports the structural integrity and artistry of the routine.