The author uses dramatic irony in this play primarily through:
B. to create humor by having Higgins overhear Chiba's monologue.
Dramatic irony occurs when the audience knows something that the characters do not. In this case, the audience is aware that Higgins is already present and observing Chiba's nervousness and self-talk, while Chiba is oblivious to Higgins’s presence. This contrast creates a humorous effect as the audience watches Chiba navigating his anxiety without realizing that his potential employer is right there.