2. what is the purpose of douglass describing the better treatment of the city slaves compared to the plantation slaves in the narrative of the life of frederick douglass?

It might be said that te main purpose of Douglass description might be to compare how cruelly the plantation slaves were treated (option A). It might be seen that Douglass makes a lot of emphasis on showing that slaves were not animals but human beings but they were valued only for their work. He argued that city slaves had more freedom, clothes, food and they even did not have to do hard work on the plantations. 

No we should just pass