Question

how is elevation shown on a topographic map?
intermediate contours
index contours
contour intervals
contour lines

Explanation:

Contour lines are the general feature used to represent elevation on topographic maps, where each line connects points of equal elevation. Intermediate contours and index contours are specific types of contour lines, and contour intervals are the elevation difference between adjacent contour lines, but the overarching method to show elevation is contour lines.

Answer:

contour lines