When Diatoms Die,their Shells Fall to the Floor of the Ocean

When diatoms die,their shells fall to the floor of the ocean or lake that they inhabit and form sediments called diatomaceous earth (DE) .Diatoms can be identified by their shells,and different species of diatoms prefer different water temperatures.What information can be gained if scientists take samples of long-existing DE and identify the diatom species that created it?

A) Scientists can decipher evolutionary lineages between diatom species.
B) Scientists can predict future trends in greenhouse gas emissions.
C) Scientists can learn about past climates.
D) Scientists can better understand how wind currents affect water temperature.