What is a duty?
a vote
a tax
a law
a crop

A duty is a commitment or expectation to perform some action in general or if certain circumstances arise. A duty may arise from a system of ethics or morality, especially in an honor culture. Many duties are created by law, sometimes including a codified punishment or liability for non-performance.

Explanation:

b. the passage of the equal rights amendment  

explanation:

this mean that anything that someone else could do they could do