Acountry is least likely to use to limit the movement of people into its borders.
a. immigration quotas
b. passports and visas
c. sanctions and embargoes
d. physical barriers

A country is least likely to use passports and visas to limit the movement of people into its borders. The correct option among all the options that are given in the question is the second option or option "b". People within a country is never required to show his passport for going from one place to another within the country.