The correct response is:
by exposing a deep personal flaw of a character
In this passage, Manny's stubbornness and refusal to adhere to medical advice, despite his obvious intolerance and discomfort, highlight a personal flaw. The satire lies in how he insists on drinking mint tea, which he doesn't even like, illustrating the absurdity of his defiance against rationality for the sake of his misguided belief in personal autonomy.