Fact 1: Fossils are formed when layers of sediment cover the remains of organisms over time.

Fact 2: Fossil fuels are formed from the remains of once living organisms that depended on light.

Given the two facts above, answer the question "Fossils are formed when remains of living things are what?" with the following options: 
- buried in mud
 - break off
 - covered over time
 - Physical weathering
 - By coral exoskeletons
 - It remains dormant
 - saved in a box
 - kept in the dark


 

   covered over time      