Which statement about the organisms whose fossils are found in the rock is correct?
A.) Organism W existed much before Organism Y.
B.) Organism Y existed over the longest period of time.
C.) Organism Y and Organism U were alive over the same time span.
D.) Organism W existed over a shorter period of time than did Organism X. The table below shows the fossils of organisms found in various layers of an undisturbed rock: