Which instrument is most commonly associated with determining angles of elevation or depression?

The clinometer is the instrument most commonly associated with determining angles of elevation or depression. This tool is specifically designed to measure the angle of inclination or declination of an object relative to a horizontal plane. It can be used in various fields, such as surveying, forestry, and construction, to assess slopes, heights of objects, and the grade of a terrain.

Clinometers typically use a gravity-based system, often incorporating a protractor and a pendulum or a level to provide accurate readings. By aligning the tool with the line of sight to the object whose height or depth needs to be measured, users can easily calculate the angle of elevation (when looking up) or depression (when looking down).

Other instruments mentioned serve different purposes: an engineer's level is primarily used for establishing horizontal planes; a laser level projects a beam of light that can help set a level line but does not directly measure angles; and a hand level, while useful for sighting horizontal lines, does not provide the functionality to measure angles of elevation or depression accurately. Thus, the clinometer stands out as the optimal choice for this purpose.