Answer:
B. The United States has almost doubled in population since 1970.
Step-by-step explanation:
The population of US has faced a rapid growth in its population. The US population has been rising from 4.7% in 1970 and 13.1% in 2013. The research has proved that there has been significant increase in population growth of the world. The US has faced a larger population growth with immigrants than any other country.