Question

which statement describes one characteristic of index contour lines?
○ they appear thinner and lighter than other lines on a map.
○ they show regions where a difference in elevation exists.
○ they show the locations of roads and paths on the landscape.
○ they show ratios used to determine the actual distance on a map.

Explanation:

Index contour lines are bold, labeled contour lines on topographic maps that mark specific elevations, and like all contour lines, they indicate areas with elevation differences. The other options are incorrect: index contours are thicker, not thinner; they do not mark roads; and they are unrelated to map scale ratios.

Answer:

They show regions where a difference in elevation exists.