The fossils found in the different layers of Earth are listed below.

Layer 1: Fossil A (oldest fossil)

Layer 2: Fossil B

Layer 3: Fossil C

Layer 4: Fossil D (youngest fossil)

Which is the topmost layer?

Layer 1

Layer 2

Layer 3

Layer 4

Option (4)

Explanation:

According to the law of Superposition, the rocks that are present at the base are the older rocks and the rocks that are deposited on the uppermost layer are the younger rocks. The younging direction of the rock is towards upward.

From the given condition, four fossils are found from four layers, of which the bottom layer contains the oldest fossils and the top layer contains the youngest fossils. The fossil A is in the layer 1 (oldest), fossil B is in the layer 2, fossil C is in the layer 3 and fossil D is in the layer 4 (youngest).

So, from the Superposition law, the rock layer that is the topmost layer is the layer 4 which contains the youngest fossil (fossil D).

Thus, the correct answer is option (4).

The answer is layer 4