The correct answer is B.
Nativism is a political stream that promotes the interests and rights of national population over immigrants. It supports the establishment of measures to control (to block) immigration flows.
Such feelings against imigration are justified by nativists due to the amount of money that they cost to the public agencies, because they steal jobs that should pertain to domestic citizens, or because they are condenmed to isolation, as they do not know the language or customs of their home country.