阅读下列短文,从每题所给的四个选项（A、 B 、C和D）中选出最佳选项。
①Teens are gaining weight. Today most teenagers are at least one size larger than teens were 20 years ago. Even clothing sizes have changed. Did you know that a small today used to be a medium, 20 years ago?
②A recent research shows 97％ of teens need more exercise. It's bad news because too little exercise means you are missing a lot of good things in life. Exercise helps in two ways.
③First, exercise helps your body. Physical activity can make your body strong. It can also keep you at a healthy weight. Doctors say that people who stay at a healthy weight have fewer health problems.
④Second, exercise can help your mind. People who get plenty of physical activity might worry less and sleep better at night. You may even learn better in school. Students who are healthy can listen and understand better in class.
⑤You can change your life and be more active at any point. It's never too late. An article called "How to Limit Screen Time and Get Moving" gives these ideas:
Step away from the screen. Doctors call watching TV or playing video games screen time. You should have no more than two hours of screen time a day. You will enjoy life more if you live it instead of watching it!
Start slowly. An hour a day can seem like a long time. Start with 10 minutes of new activities every day. Add more as you get stronger. Think about walking. Take the stairs instead of the lift. You will feel healthier.
Make fitness fun. Find a sport you like. It doesn't need to be the traditional sports of basketball, soccer, or baseball. Those are all great sports and if you like them, play them. However, you can also try hiking, skateboarding, or even rope jumping. If you enjoy the sport, you will do it.
Choose food carefully. Help your family shop for healthy food. Read the labels（标签）, ok for healthy foods. Eat lots of fruits and vegetables. Stop buying soft drinks and junk foods. You will feel better if you eat right.
Exercise with others. Find a friend or family member to exercise or play with you. You will have more fun and it helps keep you responsible for going.
