When in formation, which body part is used to set distance during a "dress right, dress"?

In a military formation when performing "dress right, dress," the left arm plays a crucial role in establishing and maintaining proper distance between personnel. When cadets execute this command, they extend their left arms horizontally, aligning their fingertips with the shoulder of the person to their left. This not only helps create an even line but also ensures that everyone maintains a consistent distance, which is essential for the overall appearance and discipline of the formation.

The left arm serves as a visual reference point for all cadets in the formation, promoting uniformity and synchronization as they adjust their positions. Using the left arm for this purpose reinforces the importance of alignment and spacing in military formations, making it a fundamental aspect of drill and ceremony training. Thus, the left arm is the correct answer because it directly facilitates the necessary adjustments for maintaining order and cohesion in formation.