In a military formation, what is a 'Rank'?

A 'Rank' in a military formation refers to a line of soldiers that stands side by side, one behind the other. This formation is one element in depth, meaning that the soldiers are arranged in such a way that they create a single line where each individual stands next to another. This organization allows for efficient movement and communication within the ranks, enabling the unit to maintain order during drills or ceremonies.

Understanding this concept is crucial, as it helps in grasping how different formations work and how troops are organized in various military contexts, such as parades or operations where discipline and structure are critical. The other options deal with different concepts within military formations but do not accurately define what a 'Rank' is.