Read the text and choose the correct answer.IV. North America has four great slopes - one slope that rivers flow down toward the Atlantic Ocean, one slope that rivers flow down toward the Hudson Bay and Arctic Ocean, one slope that rivers flow down toward the Gulf of Mexico, and one slope that rivers flow down toward the Pacific Ocean. Land also slopes toward the Great Lakes, but water there empties into the St. Lawrence River and goes on into the Atlantic Ocean.D. Which one of these is not a shape?