Question

an unusual type of fossil clam is found in rock layers high in the swiss alps. the same type of fossil clam is also found in the rocky mountains of north america. from this, scientists conclude that
○ glaciers carried the fossils up the mountain
○ the rocky mountains and the swiss alps are both volcanic in origin
○ clams once lived in mountains, but have since evolved into sea - dwelling creatures
○ the layers of rocks in which the fossils were found are from the same geologic age

Explanation:

Fossils of the same type found in different mountain ranges suggest that the rock layers (where fossils are preserved) could be from the same geologic age. Glaciers carrying fossils up mountains is less likely for such a wide - spread and specific fossil type. There is no indication from the fossil fact alone that the mountains are volcanic. Clams are sea - dwelling, and the fossil record does not support that they once lived in mountains (the presence of their fossils in mountains is due to geological processes like uplift, not their original habitat).

Answer:

the layers of rocks in which the fossils were found are from the same geologic age