The author's latest novel, a gripping historical fiction, explores themes of rebellion, sacrifice, and ultimately, redemption.
Correct: A
The word 'ultimately' acts as an interrupter or an introductory adverb that modifies 'redemption.' It should be set off by commas, especially when it is not strictly essential to the main meaning but adds emphasis or clarifies the progression of ideas. Option A, 'NO CHANGE', correctly places the comma after 'ultimately'.