Can someone help me? This is due in 30 minutes and I don’t understand how to do this problem.

c- cold periods in earth's history during which glaciers covered much of the surface.

explanation:

indicate valleys, hills, steepness and gentleness of slopes.

explanation:

contour lines on a map indicate elevation, or depth. numeric notations on contour lines refer to the level of elevation, or height about sea level.

the mantle

explanation:

earth is divided into three layers: the crust or the outermost layer on which we live; the underlying, middle layer - the mantle - and the core (the innermost layer of earth).

pie chart because it is in percents ( % )