Layers of sediment form on top of one another. Sometimes, plants and animals that have died are preserved in these layers of
sediment, and fossils are formed. When the layers are dug up, the relative age of a fossil can be determined by comparing it to
fossils found in layers above and below it. Fossils from lower layers are older, and fossils from upper layers are younger
Which of the fossils shown below is most likely the youngest?