Over the centuries the story has been told and retold and told again, often with a widely varying cast of characters. Knights, priests and priestesses, kings and queens, and various users of magic come and go, but always there is Arthur, the sun around which all else revolves, his faithless wife (Guinevere), his equally-faithless best friend (Lancelot), the illegitimate son (Mordred) who becomes his bane—and Merlin. Whatever his role, Merlin is always there, and it is always clear that Arthur could not have existed, survived, or become King without him.

Source: Bradley, Marion Zimmer. “The Once and Future Merlin.” Fictionwise. com. Fictionwise LLC, n. d. Web. 7 July 2011.

Why does the author list the “varying cast of characters” in the passage above?

A)to inform the reader that the essay will examine the story of King Arthur
B)to create a long sentence that is difficult to read
C)to persuade the reader that Merlin is the most important character
D)to educate the audience about Mordred and Lancelot