What characteristic is associated with the way the princess conducted herself?

The choice of elegance as the characteristic associated with the way the princess conducted herself is particularly fitting given the context of royal demeanor and behavior in literature. Elegance conveys a sense of grace, refinement, and dignity, which are essential traits often embodied by princesses in stories. This characteristic enhances the image of the princess as someone who carries herself with poise, embodying cultural ideals of beauty and social status.

In contrast, while confidence could also describe her demeanor, it is more of an internal trait reflecting self-assurance rather than the outwardly graceful presentation that the term elegance suggests. Authority, on the other hand, implies a command over others and a sense of control or power, which may not align with the gentler aspects of a princess's character as depicted in many narratives. Casualness, far removed from the traditional portrayal of a princess, would suggest a laid-back attitude that contradicts the expected refinement. Thus, elegance is the most accurate description of the princess's conduct, encapsulating the essence of her royal stature.