A、It’s great but not healthy for body. B、It has helped him reach his extremity. C、It’s beyond most racers’ endurance. D、It’s an

W: Hello Ladies and Gentlemen, it is a great pleasure to have Scott Jurk here to share his experience in ultra-marathons. Scott Jurek has been called the "King of Pain" and the greatest ultra-marathoner ever. Ultra-marathons can be 125 miles longer than a typical 26-mile marathon. Scott finished his first in 1994, and since then, he’s dominated the sport. Today he holds records for these races that cover more than 150 miles and last over 24 hours straight Scott:
M: Thank you for your introduction. Actually, I wasn’t always a runner. I used to hate running. I grew up hunting and fishing in northern Minnesota, and that really was where I got connected with the outdoors. And I had been interested in running through Nordic ski racing and had to get ready for the snow season by doing some running on the ski trails. Many people wonder what propels me to run the distances I do. I think it’s that self-exploration, that idea of there’s something out there and the desire to see what my body, what my mind and down to what my spirit can do. The furthest distance I’ve run is 165.7 miles in 24 hours. How that works? You know, the more time you take breaks... the clock is always going, so the idea is to continue running throughout and as much as you can, because you only get 24 hours. And the only times I did stop were to go to the bathroom, basically, and even eating is done on the run I’m actually a physical therapist and so know a little bit about the body. But is it healthy to go that far in that amount of time? You know, it’s hard to say, but the human body was built for endurance. If you look at our ancestors and what they did, I mean, even think of my great grandparents and what they did for workout in the fields, and I think maybe our perception of what is normal has changed over the years. I’m trying to work with my body. I’m not competing against myself. Obviously, there’s a clock out there. I’m not competing against other runners either. But I do use other racers in the competition to push my body to that edge because the competition really helps explore those boundaries—what am I capable of?
16 What do we learn about the ultra-marathon from this speech?
17 What do we learn about Scott Jurek’s child-hood?
18 What is Scott Jurek’s view on the competition?