I think the answer is B.
Because one of the factors that has prevented it from being a more unified country is its geography. It's rugged, mountainous. It's very difficult for any invading army to develop or control it.
Answer:
Erosion is the wearing away of an object or substance through an external force. ... The banks of creeks and rivers erode over time as the water moves past it, carrying away sediment and depositing it elsewhere. An example of where a erosion takes place is the Grand Canyon, which was worn away over the course of tens of millions of years by the Colorado River with the help of winds whipping through the formed canyon; the Rocky Mountains in Colorado have also been the subject of intense geological study, with some...
I hope this really helps :)
The current population of the United States of America is 325,372,521 as of Thursday, January 12, 2017, based on the latest United Nations estimates.
