Final answer:
The exchange between the narrator and McWhirter in Mark Twain's writing develops themes through dialogue that showcases the narrator's internal conflict, especially between responsibility and romance, suggesting reliance on personal knowledge and training over doubt. Option D is the correct answer.
Step-by-step explanation:
How the exchange between the narrator and McWhirter develops the themes of the text can be analyzed through their dialogue and how it reflects underlying conflicts. In this context, Mark Twain utilizes dialogue to pivot from confidence to anxiety, which thematically suggests that one must rely on knowledge and training rather than give in to doubt. This exchange likely leans toward option D, where the discourse conveys the conflict the narrator feels between responsibility and romance, indicating a personal, internal conflict tied to significant life decisions and themes of self-trust within the narrative. Moreover, the anecdotes in Twain's writing, particularly the river and shore scenes in his memoir, provide a literal and figurative backdrop to explore broader American ideals and the often adversarial relationship between human beings and nature. Through the broader narrative, Twain comments on human resilience and vulnerability in the face of natural forces, reflecting Naturalist themes prevalent in the literature of the time.