Why Do Trade Unions Seek to Erect Barriers to Globalization

Why do trade unions seek to erect barriers to globalization?

A) to ensure that the price of labour in the labour market is not reduced by people from less developed countries who will enable employers to cut labour costs
B) to ensure that domestic employees won't leave the domestic market and thus weaken the employee base of the economy
C) to ensure that employers who benefit from globalization also share the profits with employees
D) all of these