The significance of catharsis in theatre primarily relates to the emotional response and experience it elicits from the audience. Therefore, the best answer would be:
b. It involves the release or purging of emotions in response to a powerful performance.
Catharsis refers to the emotional release that audiences experience during a dramatic performance, often leading to a sense of relief or renewal after engaging with the intense emotions portrayed in the story. This concept was notably discussed by Aristotle in his analysis of tragedy, where he emphasized the impact of evoking pity and fear to achieve this emotional release.