Final answer:
Option (2), Viola dresses as her twin brother Sebastian, but the characters in Shakespeare's play 'Twelfth Night' believe she is a boy named Cesario. The correct answer to the question is Cesario.
Step-by-step explanation:
In Shakespeare's play Twelfth Night, the character Viola disguises herself as a boy. While Viola dresses as a boy, the other characters believe she is a boy named Cesario. Although Viola takes on the persona of Cesario, she is in fact dressing to resemble her twin brother, Sebastian.
To answer the question clearly, Viola dresses as Sebastian; however, within the play, the characters think she is Cesario. Therefore, the correct answer is option 2) Cesario.