Which statement describes a geometric boundary and provides an example?

• A. A boundary defined by physical geography such as rivers or mountains; Examples: the Rio Grande between the United States and Mexico; the Andes mountains forming part of the Chile-Argentina boundary.
• B. A boundary drawn to accommodate cultural or ethnic divisions; Example: India-Pakistan.
• C. A boundary that persists on maps despite demographic changes.
• D. A boundary defined by straight lines independent of physical features; Example: the 49th parallel north between the United States and Canada.

Answer: (D)

Geometric boundaries are defined by straight lines laid out in maps or coordinates, not by the landscape itself. They come from surveying, treaties, or grid systems and cut across terrain rather than following rivers or mountain ranges. The statement that describes a boundary defined by straight lines independent of physical features matches this idea, and the example of the 49th parallel north shows a border that runs along a constant latitude, creating a long, straight line between the United States and Canada.

The other descriptions don’t fit geometric boundaries because they describe boundaries tied to physical features or to cultural distinctions, rather than straight-line delineations. A natural boundary follows rivers or mountains. A cultural or ethnic boundary is drawn to separate groups. A boundary that stays on maps despite demographic changes speaks more to cartographic persistence than to how the boundary was defined.