What Factor Most Contributed to Making Asian Immigrants the Fastest-Growing

What factor most contributed to making Asian immigrants the fastest-growing ethnic group in the United States in the late twentieth century?

A) the transfer of the Immigration and Naturalization Service (INS) to the newly created Department of Homeland Security
B) continued civil war and political instability in Vietnam and other nations in Southeast Asia
C) creation of U.S. Immigration and Customs Enforcement (ICE)
D) limitations on immigration from the Western Hemisphere that were part of the Immigration Act of 1965