Final answer:
Based on the extract provided, Austen's tone can be described as coolly detached and ironic, which serves to engage the reader's interest. The tone reflects an ironic humor rather than outright condescension, and therefore, option a, detached and condescending, would align with Austen's narrative style.
Step-by-step explanation:
The tone of an article or any piece of writing can be crucial in understanding the author's intent and perspective on the subject discussed. In the context of the question's reference to an article, without more specific details, it is difficult to give a definitive answer; however, as the question mentions Diamond and an article, one might presume it refers to an article by Jared Diamond, a well-known author and scientist known for his works on history, anthropology, and environmental science.
Nevertheless, if we analyze the extract provided regarding Austen's narrative in Northanger Abbey, it highlights Austen's use of irony in framing her character, which could suggest a tone that is coolly detached and characterized by a subtle and ironic humor. This tone is used to pique the reader's interest by presenting the central character, Catherine, as an unlikely heroine, thereby creating a contrast between the reader's expectations and the actual narrative. The use of irony indeed becomes a strategic tool to engage the reader by juxtaposing the conventions of the genre with the unique traits of Catherine as a character.
Returning to the potential association with Jared Diamond, if the question refers to one of his works, a likely characterization of his tone, based on his general writing style, would be unbiased but concerned given his scholarly approach combined with his evident concern for environmental and societal issues.
Ultimately, without the specific article in question, the most fitting choice within the provided options would be subjective to the piece's content. However, reflecting on the technique utilized by Austen, one could lean towards option a, a detached and condescending tone, which aligns with the use of irony in the text described.