I NEED HELP ASAP b) Contour lines represent areas of elevation

Contour line, a line on a map representing an imaginary line on the land surface, all points of which are at the same elevation above a datum plane, usually mean sea level. The diagram illustrates how contour lines show relief by joining points of equal elevation. Encyclopædia Britannica, Inc. Video Player is loading.

layer a is the exosphere and layer b is the thermosphere.   is the answer i think but i hope this .