What is the best descriptor of the pattern of immigration or restrictions as it applies to the United States?
A.
Historically, the United States has been tightening immigration restrictions consistently across each decade.
B.
The number of immigrants attempting to move to the United States has increased year after year since the 1930s.
C.
The number of illegal or undocumented immigrants in the United States has been climbing higher and higher in recent years.
D.
Both the number of immigrants and the US policies towards them, have evolved and changed over the years.
