Correct answer:
According to Aristotle, a tragedy must center on the suffering of a tragic hero or heroine.
In his work on Poetics, Aristotle defines tragedy in this way: "Tragedy is a form of drama exciting the emotions of pity and fear. Its action should be single and complete, presenting a reversal of fortune, involving persons renowned and of superior attainments, and it should be written in poetry embellished with every kind of artistic expression."
In his thoughts on Poetics (or what we would call the dramatic arts), Aristotle also asserted that every tragedy (a dramatic, serious play) contains six elements: "Plot, Character, Diction, Thought, Spectacle, Song."