Who becomes a professional racecar driver and a Formula One champion in Italy?

In the context of "The Art of Racing in the Rain," the character who becomes a professional racecar driver and a Formula One champion in Italy is Denny. Throughout the story, Denny demonstrates determination and a deep passion for racing, which ultimately leads him to achieve success in the competitive world of professional racing. His journey is marked by challenges and personal growth, showcasing not only his skills on the track but also his resilience in facing life's adversities.

The other characters, while significant in the narrative, do not reach the level of becoming a professional racecar driver or a Formula One champion. Luca, for instance, is a friend and support system for Denny, but he does not pursue the same career path. Enzo, the dog and narrator of the story, offers philosophical insights on life and racing but is not a driver himself. Zoe is also an important character in Denny's life, but she does not take on the role of a professional driver. Thus, Denny's accomplishments highlight his talent and dedication, making him the correct answer to the question.