Which statement is true regarding contour line colors on topographic maps?

Contour lines on topographic maps serve the essential function of denoting elevation levels. Each line represents a specific elevation above a base reference point, typically sea level. The spacing between contour lines illustrates the steepness of the terrain; closely spaced lines indicate steep slopes, while widely spaced lines suggest gentle slopes or flat areas.

Using colors for contour lines is a conventional practice that helps map readers quickly identify changes in elevation and comprehend the landscape's topography. While contour lines themselves are typically a single color, their elevation significance is crucial for understanding landforms, water flow, and other geographical features.

In contrast, the other statements do not accurately reflect the function of contour lines. Temperature conditions, decorative purposes, or vegetation types are unrelated to the primary role of contour lines in representing geographical elevations. Thus, recognizing contour lines as indicators of elevation levels is fundamental to interpreting topographic maps effectively.