Answer: I don't know if this is a multiple-choice question or not, but I would contend that the right word is HEARKENS.
Explanation: Just to elaborate a little on the answer, it can be added that this excerpt is part of a dialogue between Clarence's, Richard's brother, and Richard. Clarence has just arrived and has told his brother that their other brother, King Edward, is sending him to the Tower of London — a prison back then. Richard asks him what is going on, and Clarence replies that he does not know yet. All that he knows is that their brother listens to prophecies and dreams, and a wizard has told him that a "G" is going to depose his children. Since Clarence's name is George, the king believes that he is "G," and that is why he is sending him to prison.