The Equal Pay Act,as Codified in the Civil Rights Act

The Equal Pay Act,as codified in the Civil Rights Act of 1991 permits an employer to pay females less than males for the performance of jobs that require equal skill,effort and responsibility,provided that

A) the difference is based on a seniority system.
B) the difference is based on a merit system.
C) the difference is based on a piece work system.
D) All of the choices are correct.