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 bolded/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; they are not map scales.

Answer:

They show regions where a difference in elevation exists.