By comparing fossils in higher sedimentary layers with fossils in lower sedimentary layers scientists can learn which of the following

Scientists can learn, which types of organisms were more common during time periods, how species have evolved over time, and the relative age of different species. Sedimentary rocks can contain fossils because, unlike most igneous and metamorphic rocks, they form at temperature and pressures that do not destroy fossil remains. Dead organisms can become sediments which may, under the right conditions, become sedimentary rocks. 

Bis the answerhope it

C) they are specialized meaning they are designed to do different things