Answer:
4. It is a fossil because footprints of organisms from million of years ago are considered to be fossils.
Step-by-step explanation:
A geologic column can be defined as a collection of rock layers that are typically grouped based on their relative ages in a descending order i.e from oldest to the youngest.
Generally, the layers of the rock that are found in various parts of the world are known to be different because they all comprises of distinct Earth's geological history.
In this scenario, while exploring a rock formation, Hiroto finds a rock that has footprints pressed into it. A geologist tells Hiroto that the rock is millions of years old. Therefore, the claim about Hiroto’s finding that is correct is; it is a fossil because footprints of organisms from million of years ago are considered to be fossils.
A fossil can be defined as the mineral impression or remains of living organisms such as plants and animals that are prehistoric in nature.