The correct answer is C) Exclusion.
Nativist groups are collections of people who are anti-immigration. Nativists are individuals who put the needs of native born citizens over those of immigrants. This group of people usually resent immigrants because they take job opportunities away from native born citizens. Nativist argue that immigrants are willing to work for less pay, resulting in businesses hiring immigrants instead of citizens born in the country.
This is why nativists are in favor of excluding new people from coming into their country.