Answer:
Option (D)- which is fossil 4, as given in the image
Explanation:
From the law of superposition of rocks, it is known that the rock layer forming the bottom of an undisturbed sedimentary sequence are the oldest rocks because they those sediments were first deposited there and due to compaction and lithification it formed a rock layer, and subsequently new sediments are deposited on top of it. The rocks that are found to be present at the apex portion of a rock sequence signifies the youngest rocks, where the recent sediments are deposited.
So the fossils present in the bottom layers will be oldest and those fossils that are present on the top rock layers are the youngest.
Thus, the fossil sample number 4 (trilobites), as given in the image is the oldest fossil.
Hence, the correct answer is option (D), which is fossil 4.
