13. If layers of rocks are millions of years old, then which of the following is true? Earth is very old.
The bottom layers are the newest.
b. Earth is very young.
d. none of the above.
a.
C.

Option D, Fossil in layer 6 are less than 540 million years old

Explanation:

In any fossil deposition, the youngest of fossils lies at the topmost layers while all other layers below it are much older than it.

Here, layer 1 lies at the bottom and layer 13 lies at the top. Thus, layer 1 is the oldest and layer 13 is the youngest fossil.

In the question , it is given that index fossil of age 540 million years old are found at the layer 5, therefore all layer lying above it will be less than 540 million years.

Therefore, option D is correct.

option D is correct answer of this question

the correct answer is c.