Aristotle viewed characters as the agents of the plot, that provide a vehicle for the unfolding narrative or themes; the plot is the arrangement of events in which characters face challenges, overcome obstacles, the plot could be on stage or off-stage told through narrative dialogue. From this, we can conclude that a character can be D. Imaginary as the character's story can be told through another character delivering dialogue; as a character can come in any shape or form it could be C. Round; It could, in theory, be classed as A. unimportant as a main character, provided that such a background character added to the effect upon the other characters; I would not see it likely that the character would be B. musical, as by nature a character cannot be music (unless discussing the character of music).