Which terrain feature would typically indicate an elevation drop?

The chosen answer, which refers to a depression, is indeed the correct identification of terrain indicating an elevation drop. A depression represents a lowered area in the landscape, making it a concave feature. This is characterized by its surroundings being at a higher elevation compared to the center of the depression, clearly indicating a drop in elevation.

Understanding terrain features is crucial for navigation and flight operations, as recognizing these features can significantly affect flight planning and safety. Other features like a saddle typically refer to a low point between two higher elevations but do not necessarily indicate a drop; rather, they connect two higher areas. A hill represents an elevation gain, and a spur refers to an extended ridge or projection from a high ground, highlighting an increase in elevation rather than a decrease. Thus, regarding identifying terrain drops specifically, the depression accurately illustrates this key aspect in terrain assessment.