Which exercise involves stabilizing the lower body while allowing for upper body mobility?

The exercise that involves stabilizing the lower body while allowing for upper body mobility is torso rotations. This exercise focuses on enhancing the rotational movement of the upper body while the lower body remains stable. It is essential in developing core strength and improving the ability to separate upper and lower body movements, which is crucial for a refined and efficient swing in sports like golf.

Torso rotations allow for the engagement of core muscles, which contribute to the stability of the lumbar spine and pelvis while enabling the shoulders and arms to move freely. This distinction between the stability of the lower body and the mobility of the upper body is vital for maintaining balance and generating power in a swing.

The other options are primarily focused on different aspects of stability and strength without providing the same upper body mobility. For instance, hip bridges and wall sits emphasize lower body strength and stability, while side lunges involve both lower body movement and stability but do not primarily focus on upper body mobility in the same way. Thus, torso rotations stand out as the correct answer, highlighting the essential concept of stabilizing the lower body while enabling upper body movement.