What does a profile of a river from its headwaters to its mouth typically show?

A) an increase in gradient downstream
B) a straight-line profile reflecting a constant decrease in gradient
C) an abrupt increase followed by a gradual decrease
D) a curved shape that flattens out downstream
E) none of these

Gradient

The rate of change of a quantity (e.g., temperature, pressure, or elevation) with respect to distance in a given direction.

Headwaters

The source of a river or stream, generally found in the high elevation areas from which the river originates.

Mouth

The location where a stream, river, or canyon ends, such as where a river enters the sea.