Final answer:
Banquo serves as the foil to Macbeth in Shakespeare's tragedy, highlighting Macbeth's tragic flaws by offering a stark contrast in character.
Step-by-step explanation:
In a Shakespearean tragedy, characters often serve specific roles, and one such role is the foil, which emphasizes the traits of the main character through contrast. In the case of 'Macbeth,' Banquo serves as the parallel character to Macbeth and operates as his foil. Banquo reflects the noble qualities that Macbeth could have followed, and by juxtaposing the two, Shakespeare amplifies Macbeth's tragic flaws. Banquo is honorable, a stark contrast to Macbeth's ambitious betrayal, and thus, he amplifies Macbeth's descent into tyranny and moral decay. Therefore, the correct answer to who is the parallel character of Macbeth is a) Banquo.