What group was largely responsible for getting this law passed?

National Organization for Women

U. S. Department of Labor Women's Bureau

National Women's Party

Presidential Commission on the Status of Women

The Correct Answer is

National Organization for Women

Explanation:

The National Organization for Women is a political activist organization that struggled for gender equality in the United States of America. This organization fought for equality in the offices and workplaces, acknowledging that men and women performing comparable functions made very different salaries.

At this time, men got paid a much higher salary in comparison to a woman who served at a alike occupation. That's why this law was formulated, to reduce the unequal treatment of women in the work place.