If prehistoric life is preserved in rock when layers of sediment cover the remains over time, then prehistoric life is preserved in rock when what covers the remains over time?

Answer choices:
- Plant growth is reduced
 - an amoebae
 - layers of sediment
 - single-celled organisms
 - loose soil
 - layers of fungus
 - layers of bone
 - layers of mucus

 

   layers of sediment       