Last summer, when Amanda R of Anaheim Hills, California, was running on a cross-country course with her team, she blacked out. "I got really dizzy," she says. "I was out for a few minutes." At first, Amanda thought she was just tired and didn't think she had a health problem. She did go to the emergency room, where she was fine after tests, but she fainted   again several days later as she was talking with her coach. Another doctor guessed that Amanda had blacked out "because we were in heat so much with not enough water and not enough of the right kind of foods". Teens often don't want to stop and take a break or don't notice when they start to feel bad, doctors say. However, paying attention if you're not feeling well is important, as Amanda learned. As a result, Amanda has changed her habits. "I drink a lot more water," she says. "And put more salt in my diet. I'm eating more balanced meals." Amanda advises teen athletes to trust their coaches and speak up when they're not feeling well. "And recognize the difference between when you're tired and when there's something really wrong." Some people - up to 3 percent of the population - sweat too much, even in cold weather. The condition, called hyperhidrosis  , can affect many parts and it often runs in families - hands down from generation to generation. Too much sweating over the whole body could be a symptom of another medical condition. Doctors aren't sure what causes hyperhidrosis, but using special medications or other treatments can help. The purpose of writing this passage is to   _   .
tell teens the proper ways to take exercise in summer. tell teens not to run in hot summer. tell teens to pay attention to hyperhidrosis in the summer exercise tell teens how to keep healthy.
Question: Last summer, when Amanda R of Anaheim Hills, California, was running on a cross-country course with her team, she blacked out. "I got really dizzy," she says. "I was out for a few minutes." At first, Amanda thought she was just tired and didn't think she had a health problem. She did go to the emergency room, where she was fine after tests, but she fainted   again several days later as she was talking with her coach. Another doctor guessed that Amanda had blacked out "because we were in heat so much with not enough water and not enough of the right kind of foods". Teens often don't want to stop and take a break or don't notice when they start to feel bad, doctors say. However, paying attention if you're not feeling well is important, as Amanda learned. As a result, Amanda has changed her habits. "I drink a lot more water," she says. "And put more salt in my diet. I'm eating more balanced meals." Amanda advises teen athletes to trust their coaches and speak up when they're not feeling well. "And recognize the difference between when you're tired and when there's something really wrong." Some people - up to 3 percent of the population - sweat too much, even in cold weather. The condition, called hyperhidrosis  , can affect many parts and it often runs in families - hands down from generation to generation. Too much sweating over the whole body could be a symptom of another medical condition. Doctors aren't sure what causes hyperhidrosis, but using special medications or other treatments can help. The purpose of writing this passage is to   _   .
A. tell teens the proper ways to take exercise in summer.
B. tell teens not to run in hot summer.
C. tell teens to pay attention to hyperhidrosis in the summer exercise
D. tell teens how to keep healthy.
Answer: