In which novel of Jane Austen is Captain Frederick Wentworth a character?

The correct option is Persuasion.

Captain Frederick Wentworth is the central male protagonist in Jane Austen's novel, Persuasion, published posthumously in 1817. He is a self-made naval officer who has risen through the ranks during the Napoleonic Wars. The novel revolves around his reunited romance and ultimate reconciliation with Anne Elliot, the female protagonist, whom he was persuaded to reject eight years prior due to his lack of wealth and social status.

To verify why the other options are incorrect:
• Emma features characters like Emma Woodhouse and Mr. George Knightley.
• Northanger Abbey features Catherine Morland and Henry Tilney.
• Mansfield Park features Fanny Price and Edmund Bertram.
Therefore, Captain Frederick Wentworth is uniquely associated with Persuasion.