Select the correct answer. Why is the standard of living in the United States generally higher than the standards of living in other parts of the world?

A.
The US economy can meet the basic needs of most of its citizens.
B.
The United States has a large population that is made up of people from many backgrounds, so its culture is diverse.
C.
The United States is strategically located between two major oceans.
D.
Ten large US cities have a population of more than one million, including New York, Los Angeles, Houston, and Chicago.