If if remains of prehistoric life are found in a place then that place used to be covered by water, then what being found in a place shows that place used to be covered by water?

Answer choices:
- volcanoes
 - wind
 - plankton and nonliving organic
 - dead organisms
 - marshes and swamps
 - sedimentary rocks
 - dirt
 - remains of prehistoric life

 

        remains of prehistoric life  