I think it is number 3 or c because earths layer is just the right tempature for us to live on, and the mantle is very hot liquid that is under the crust or the 1st layer of earth and it gets hotter the deeper you go like the inner core is molten metal and is very very hot. hope this helps
<span>one way is.... many skeletons of dead animals melted together and formed the coral reef. another is ..... volcanic eruption.</span>
