The correct answer is tragic hero.
Hamlet is the hero of the eponymous play written by William Shakespeare. He is definitely tragic - his father is killed, and he is contemplating either revenge or suicide. In the end, he opts for revenge, murdering his uncle Claudius who is the actual culprit, but ultimately dying himself, having been murdered by Laertes.
Answer:
It creates uncertainty because the audience cannot be sure if the ghost is actually present, or if Macbeth has simply gone mad.
