Answer: The right answer is the D) Person who changes his mind.
Explanation: Just to elaborate a little on the answer, it can be added that in this scene from Act II Romeo has just confessed to Friar Lawrence that he is not in love with Rosaline anymore. Instead, he is in love with "the fair daughter of rich Capulet," that is to say, Juliet, and she loves him back, so he asks him to agree to marry them that same day. Friar Lawrence is very surprised, since he thought that Romeo was deeply and painfully in love with Rosaline, and he reprimands him for being so unreliable. Romeo begs him to stop scolding him and he reasserts that they are in love. Finally, Friar Lawrence agrees to help him, and it is then when he addresses him in those terms ("young waverer"), in a last attempt to remind him of the inconsistency of his feelings and of his acts.