Which of the following formed from the remains of plants and animals that died millions of year ago?

a. uranium

b. coal

c. solar power

d. biofuel

Coal from swamp plants that formed millions of years ago.

Coal. when large plants died millions of years ago, they formed layers on the bottoms of swamps where more matter like water and dirt piled on top. in the millions of years following, the heat and pressure build-up on these layers caused them to undergo physical and chemical changes, creating coal.