What does the thumb loop on a compass assist with?

The thumb loop on a compass serves to stabilize readings while moving. When navigating, especially in dynamic environments or challenging terrains, maintaining a steady hand can be crucial for accurate readings. The thumb loop allows the user to secure the compass with their thumb, which helps to keep the device steady and aligned during movement. This stability is important as it minimizes errors caused by hand tremors or environmental distractions, enabling the user to take precise bearings or follow a map more accurately.

In contrast, the other options pertain to functions that are not associated with the thumb loop. For instance, measuring distances accurately typically involves integrating other tools or scales on the compass rather than using the thumb loop itself. Adjusting the compass scale and changing the elevation angle are also operations that do not involve the thumb loop; they require separate adjustments based on specific context or terrain rather than the inherent design of the thumb loop.