D. All of the above.
In Act 3 of "Romeo and Juliet," Juliet experiences significant character development. She becomes stronger and begins to assert herself more, especially in her responses to her parents regarding her marriage to Paris. She is also determined to control her own fate, particularly in her love for Romeo. Additionally, Juliet feels disillusioned and betrayed by the Nurse when the Nurse suggests she should marry Paris after Romeo's banishment. This culmination of her emotions and defiance illustrates her growth as a character.