The diagram below shows a cross section of a portion of Earth's crust that has not been overturned. Letters A, B, C, and D represent rock layers that contain certain
fossils.
TH
(Not drawn to scale
Which rock layer contains the oldest fossils?
а. А
c. c
b. B
do
a
Oь

D

Explanation:

D layer is the last layer of the soil that is present at the bottom of other layers having the oldest layers. The bottom layer of soil is formed first and when we go up the age of soil layers decreases because it is formed after the parent soil. The fossil that is present at the bottom layer is considered as oldest fossil as compared to those fossils that are present in the above layers of that soil.