Read the following excerpt: And Hamlet, left alone, began to wonder and to question as to what he ought to do. For he could not believe the story about the snake-bite. It seemed to him all too plain that the wicked Claudius had killed the King, so as to get the crown and marry the Queen. Yet he had no proof, and could not accuse Claudius. And while he was thus thinking came Horatio, a fellow student of his, from Wittenberg. "What brought you here?" asked Hamlet, when he had greeted his friend kindly. "I came, my lord, to see your father's funeral." "I think it was to see my mother's wedding," said Hamlet, bitterly. "My father! We shall not look upon his like again." "My lord," answered Horatio, "I think I saw him yesternight." Then, while Hamlet listened in surprise, Horatio told how he, with two gentlemen of the guard, had seen the King's ghost on the battlements. Hamlet went that night, and true enough, at midnight, the ghost of the King, in the armor he had been wont to wear, appeared on the battlements in the chill moonlight. Hamlet was a brave youth. Instead of running away from the ghost he spoke to it—and when it beckoned him he followed it to a quiet place, and there the ghost told him that what he had suspected was true. The wicked Claudius had indeed killed his good brother the King, by dropping poison into his ear as he slept in his orchard in the afternoon. "And you," said the ghost, "must avenge this cruel murder—on my wicked brother. But do nothing against the Queen—for I have loved her, and she is your mother. Remember me." Then seeing the morning approach, the ghost vanished.

This passage suggests that

Hamlet was wrong about his suspicions
Hamlet was correct in suspecting his uncle
seeing a ghost was very frightening to Hamlet
the ghost of the King was a dream of Hamlet's