You are looking at the side of a cliff with many clearly visible layers of rock. In the top layer you find the fossil of a mouse. In the next layer down you find the fossil of a frog. Two layers down from that you find the fossil of a beetle, and in the deepest layer the fossil of a millipede. This is evidence that
A)mice evolved before frogs. B)frogs evolved after mice. C)millipedes were the first among these animals to evolve. D)the beetle evolved before millipedes.