Choose the right answer. a series of light brown lines drawn at intervals of 50 feet to designate their respective heights above sea level are called
a contour lines
b elevation lines

Contour lines

Step-by-step explanation:

A series of light brown lines drawn at intervals of 50 feet to designate their respective heights above sea level are called CONTOUR lines, or just contour.

A contour line (also called isoline) is a line that indicates points at the same elevation on the map, showing you a representation of the terrain's elevation (hills, mountains, canyons and so on).  You will find those lines on specialized maps, like topographic maps, which are different than road maps.