What is a route map used for?

A route map is specifically designed to indicate where various transportation systems travel. This is essential for understanding travel options and logistics within a given area. Route maps typically outline the paths taken by different transportation services, such as bus lines, train routes, or flight paths, allowing travelers to visualize how to navigate from one location to another using available transportation options.

In contrast, the other answer choices focus on different representations of geographic data. The first choice pertains to geographical features, which may include mountains, rivers, or other natural landmarks, but does not specifically relate to transportation routes. The third option addresses topographic changes, which are concerned with elevation and physical landscape variations, rather than routes of transit. Lastly, the fourth choice discusses population density, which involves demographic analysis rather than the specific transportation paths needed for travel planning. Therefore, the primary function of a route map is to clearly communicate the pathways of transportation systems, making option B the most appropriate answer.