What are the four rest positions that can be commanded at the halt?

The four rest positions that can be commanded at the halt are indeed Rest, Parade Rest, At Ease, and Stand at Ease.

Rest is a position that allows personnel to relax while still maintaining military bearing; it serves as a temporary position that is more comfortable than Attention but does not permit movement. Parade Rest is a position that is more formal and requires personnel to stand with their feet apart and hands behind their back, projecting a sense of discipline and order. At Ease allows for a more relaxed posture while still maintaining the ability to listen and respond to commands, typically involving the personnel keeping their right foot in place and their hands to the rear. Stand at Ease is similar to At Ease but includes more restrictions on movement due to the need to maintain a serious demeanor and readiness to move when necessary.

This set of commands is structured to allow personnel different levels of relaxation while still exhibiting military discipline, making them vital for maintaining order during formations or briefings. The other choices include terms that are either incorrectly paired with the context or include commands that are not utilized at the halt, such as Marching or Attention, which signifies a position of readiness rather than relaxation.