With which american institution were frederick douglass, levi coffin, and harriet tubman most closely associated?

The Civil rights movement. Harriet Tubman played a role in the Underground railroad, Frederick Douglass wrote several autobiographies. He described his experiences as a slave in his 1845 autobiography, Narrative of the Life of Frederick Douglass, an American Slave, which became a bestseller, and was influential in promoting the cause of abolition, as was his second book, My Bondage and My Freedom, while Levi Coffin was also an active leader in the underground Railroad

Answer for apex - the reformation