Which principle of stratigraphy could be used to determine the relative ages of Layer 7 and Layer 3?

a. the principle of fossil succession.

b. the principle of original horizontality.

c. the principle of lateral continuity.

d. the principle of inclusions.

Option (A)

Explanation:

According to the fossil succession, the rocks that are comprised of similar fossils that are found in different places are of the same age. This law enables a geologist to determine the relative age of the rock layers in an undisturbed sedimentary sequence.

In the given condition, considering the layers as 1, 2, and so on, from the bottom towards the top, the relative age of the layers could be determine, where, the layer 3 will be older than the layer 7 as the fossils embedded in the layer 3 were deposited earlier, and the fossils embedded in the layer 7 were deposited later, in terms of geological time.

Thus, based on the principle of fossil succession, the relative ages of the layers can be determined.

Hence, the correct answer is option (A).