What does a horizontal plane typically represent?

A horizontal plane typically represents the Earth's surface because it is an abstract, flat, geometric concept used to illustrate a reference level. In many mapping and navigation contexts, a horizontal plane is considered the baseline from which elevations and other measurements are derived.

This plane helps establish how terrain and geographical features are oriented in relation to sea level, providing a consistent frame of reference for various applications, including cartography, construction, and navigation. Understanding horizontal planes is essential for interpreting maps accurately and for situational awareness in many fields.

In contrast, other options such as the structure of a building, underwater navigation, and aerial navigation pertain to more specific vertical or situational contexts that do not fundamentally relate to the concept of a horizontal plane in the same way.