What is the work of a boundary line in a map?

Correct answer: To separate areas

Direct answer: C is correct. A boundary line is a line used to mark the edge or limit of one area and distinguish it from another area. On a map, it may separate administrative regions, countries, states, districts, or other mapped zones, depending on the map's purpose. The important idea is separation and identification: the line helps the reader know where one region ends and another begins. Option A is wrong because changing the lightness of a colour is a matter of tone or value, not the main work of a boundary line. Option B is wrong because a drawn map line does not physically cut the paper. Option C is correct because it states the central function of a boundary line. Option D is wrong because texture is a surface quality, and a boundary line does not erase it. The exact meaning of a boundary can depend on the map legend, so readers should also check the symbols and key. Memory cue: boundary means border; a border separates and identifies areas.