Final answer:
John sarcastically refers to the new world as 'brave,' using a Shakespearean reference, and Bernard's concern for John's integration into the society foreshadows the challenges ahead, making option C the correct answer.
Step-by-step explanation:
The irony in John's proclamation that he is going to a "brave new world" lies in the fact that he is using a Shakespearean reference to express his sarcasm about the new world's supposed wonders, which in reality is a deeply flawed society. The term 'brave new world' originates from Shakespeare's play 'The Tempest,' where it is spoken with genuine amazement and optimism; however, in the context of Aldous Huxley's novel, it signifies John's recognition of the dystopian aspects of the new society he is about to enter. This sarcasm is picked up by Bernard, who, instead of encouraging John, expresses concern for his integration into the world, suggesting that there will be challenges ahead for John. Bernard's response introduces foreshadowing because it hints at the difficulties and conflicts John will face in the future.