Final answer:
Sir Gawain, the Green Knight, and the old woman at Bercilak de Hautdesert's castle are dynamic/round characters because they experience significant development throughout the story.
Step-by-step explanation:
Since Sir Gawain, the Green Knight, and the old woman at the castle owned by Bercilak de Hautdesert change as a result of the plot, they are considered to be dynamic/round characters who do change. Dynamic characters are those who undergo significant development or change in personalities, attitudes, or perspectives throughout the story. In contrast, static/flat characters do not change much or at all. The shift in characters often reflects the main themes of the story and contributes to the narrative's depth. For instance, Sir Gawain's changes reflect on themes of honor, chivalry, and humanity's fallibility.