It is Exothermic Change because,Exothermic is a chemical reaction that releases energy it could be light or heat. :)
D. Has a uniform composition and is only able to be separated by chemical means.
You already write there it's answer ಠಿ_ಠ
A plateau is a flat, elevated landform that rises sharply above the surrounding area on at least one side. Plateaus occur on every continent and take up a third of the Earths land. They are one of the four major landforms, along with mountains, plains, and hills.