Although douglass gained fame for his role in the fight to end slavery, he also played a major role in the movement.

Women suffrage

Explanation:

Years after slavery ended, Frederick Douglass still use his power and influence to improve the societal condition in united states, including women suffrage movement.

For example, in  1866 he was working together with another major figures in women sufferage such as Susan B. Anthony and Elizabeth Ttaton to founded American Equal Rights Association. This organization focused its effort to ensure that all citizens in united states had the same right, regardless of Gender, Race, or Religion.

b) to encourage free trade

i have to go with a for this one