Final answer:
Porter's scene in Macbeth functions as comic relief, using prose and bawdy humour to provide a break from tragedy and reflect on underlying themes. Porter's lines contrast with the noble characters' speech and inject levity into the play.
Step-by-step explanation:
The Porter's scene in Shakespeare's plays often serves as a form of comic relief, and its placement in Macbeth is intentional. After a series of intense events, such as the murder of King Duncan, this scene provides the audience with a much-needed respite. It resets the emotional atmosphere, offering levity and contrast to the tension that has built up. The scene also serves as a reflection on the themes of equivocation and the portrayal of the 'porter of hell's gate' as a parallel to Macbeth's castle after the heinous deed. The choice to have Porter speak in prose rather than iambic pentameter is meant to highlight his lower social status and create a distinct voice from the noble characters. The bawdy humour is exemplified in Porter's innuendo-laden lines, such as his references to drinking and its effect on sexual prowess.
As for the correct option from the provided choices, it would be (a): The scene provides a lighthearted break after a series of intense events and introduces humor to balance the tragedy. The Porter's lines are in prose to contrast with the noble characters' poetry. The bawdy humour can be seen in the lines where Porter makes sexual innuendos.