I assume that the question refers to the political affiliation of the Islands (They are Islands in the Mariana Trench, in the Pacific Ocean, south of Japan) - they are politically linked to the US - the correct answer is a). For example the Mariana islands have a commonwealth status within the US.
The lowland river system.
Energy nurence and viamins ar the thigs that cone frome it
Answer:
a. They must be present in a large geographic area.
Explanation:
Index fossils can be used to determine the age of a rock strata with great precision, but they must be scattered over a large geographic area to be able to be used reliable for this type of measurement. Index fossils typically indicate a certain type of paleoenvironment belonging to a very specific prehistoric period and their formation coincides with the age of the rock layer.