Question

if you found an index fossil in a layer of rock in montana and a similar fossil in a layer of rock in texas, you would know that: the fossils from montana are older; the fossils and rock layers are the same age; the fossils from england are older; none of the above

Explanation:

Index fossils are used to date rock layers. If the same index fossil is found in different locations, it implies that the rock layers containing them are of the same age.

Answer:

the fossils and rock layers are the same age