The province of ____________________ receives high levels of pollutants from nearby U.S.states.

Most of the world's easily accessible high-grade mineral deposits have not been discovered.

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