The correct answer is "It opened the door to almost unlimited immigration."
The Immigration Act of 1965, also known as the Hart-Celler Act, signaled a fundamental shift in the country's migration policy, which was working under the "Emergency Quota Act" of 1921. This previous policy, restricted immigration possibilities for all people who were not from northern or western Europe. This new law established country quotas and favored migration for individuals who possess certain skills which were valuable for the country. The demographic landscape of the country would change considerably after the introduction of this law.
