When is the use of a compass most applicable in determining direction?

The use of a compass is particularly applicable in determining direction when visibility is low. In situations where fog, heavy rain, darkness, or other factors obscure one’s view, a compass becomes an essential tool for navigation. It provides an independent means of establishing cardinal directions without relying on visual landmarks, which may not be visible or discernible.

In low visibility conditions, making directional decisions based on external references can lead to disorientation or getting lost. Using a compass helps maintain a clear sense of direction and can assist in navigating through unfamiliar terrain safely. Moreover, all other options focus on distance estimation and map scaling, which do not directly relate to the critical function of direction-finding that a compass serves under low visibility conditions.