The correct option is E influence on peoples morals
"Most important, its a corrupting influence, perverting its audience by bombarding it with inferior characters and vulgar subjects and constituting, in Plato's own words, a harm to the mind of its audience. " - this statement from the passage indicates that Plato's main objection to poetry was due its, according to Plato, bad influence on people's mind and morals. Thus D is the answer.