The Answer is Solar Energy
<span>Geography and their environment are very influential on a region’s economic activity. For example, most major U.S. cities, including New York City, Chicago, and Boston, are all located near water. This is because when these cities were founded, water was the main mode of transportation. The environment also has many economic consequences, including the type of crops that can be grown and whether or not different activities can take place outdoors.</span>
I think the United States is a well developed country. Like if you see India or Africa they are still developing.
I hope this helps :)
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.
