Why Would Domestic Labor Groups Promote International Human Rights Standards

Why would domestic labor groups promote international human rights standards?

A) Human rights standards are clearly the ethical norm for groups to support.
B) Adopting such rights would level the economic and political playing fields for workers.
C) Firms are reluctant to invest in other countries that have poor human rights practices.
D) Laborers want to make sure that their rights will be respected if they have to ever move to another country.
E) Firms force labor unions to promote human rights,even if it is against the interests of the workers.