An emergency Quota Act in 1921 and the National Origins Act of 1924 provided for a quota system limiting immigration. According to this system,

A)an increased number of foreigners could enter the U.S.
B)an equal number of immigrants from all nations could enter the U.S.
C)only Europeans were allowed to immigrate to the U.S.
D)some nations could send more immigrants to the U.S. than others could

The number of immigrants that were allowed entry into the US through the national quota system was limited by the Immigration Act of 1924. The quota allowed the immigrant visas to two percent of the total number of people of each nationality in the US as per the 1890 census. It excluded the migration from Asia. The provisions of the immigration act of 1924 paved way for the 1924 act. The 1917 act included a literacy test on arrival and also increased tax which was to be paid upon arrival.

In the 1920s when a new way was sought to restrict the immigrants. It was introduced by Republican Senator William P. Dillingham. The quota system set created immigration quotas which were set at three percent of the total population of the foreign-born of each nationality in the US as per 1910 census records.