Respuesta :
The book that would be the most useful for a teenager who is considering running a marathon would be Marathons for Dummies (D).
Since we can assume the teenager has never run a marathon before, a book with general information about marathons and how to prepare for them would be the most useful. He does not have enough knowledge to only focus on eating right or weight training for the marathon, so B and C do not work. A marathon is not the same as cross-country, so A would not be the best choice.
Answer:
I would definitely say D. Marathons for Dummies.
Explanation:
Assuming they have never run a marathon before or even thought about it, a book that provides general and simple information on how to do so would be the best choice.