How did congress try to limit immigration in the 1920s?
by excluding all europeans
through denaturalization
through deportation
by creating a quota system

This is based on the Immigration Act of 1921 and how the Congress tried to limit immigration during this times is through establishing a quota system. The answer to this would be the fourth option. This is the time when The Emergency Quota Act of 1921 was established which only allows 3% of immigrants from Europe alone. 

Herodotus taught that absolute right and wrong did exist.