The table below shows the fossils of organisms found in various layers of an undisturbed rock: Fossils In Rock Layers Layer (from top) Fossil in Layer 1 X, W 2 W 3 Z 4 Y, U Which statement about the organisms whose fossils are found in the rock is correct? Organism W existed much before Organism Y. Organism Y existed over the longest period of time. Organism Y and Organism U were alive over the same time span. Organism W existed over a shorter period of time than did Organism X.