Read the passage carefully and choose the correct answer.

     In a recent government survey on healthy eating teens scored only out of 10. Only 1 in 10 teens eats the recommended amount of fruit and the only vegetable that many teens eat is “chips”. Most teens in the developed  world are eating too much but are still not getting the vital nutrients to help them grow and stay healthy. More information about nutrition and healthy eating is needed to help young people eat properly. Teens who diet often cut out food they need, such as bread or milk, because they think it is fattening. Others dont know what foods to choose in the school canteen in order to have a balanced diet. There is a saying “you are what you eat“”. So if you want to become the next David Beckham then you'd better start eating properly.  Lack of money in schools plus increased pressure to do well in the course exams means that teenagers are doing less sport in school than ever before. Girls, in particular, are more likely to suffer from lack of exercise and up  to 4 in 10 girls stop playing sports in their early teenage years. Just because you arent sporty doesnt mean you can t be active. Walk or cycle to school instead of taking the bus. Help at home with the housework or gardening. Go dancing with your friends. There are lots of ways you can stop being a couch potato.

     If "we are what we eat” then sleep is like food for the brain. Teens need at least 9 hours' sleep every night and even mild sleepiness can affect your performance, humour and health. Lack of sleep can make you tired, angry or depressed. Nearly 40% of secondary school students go to bed after 11 p.m. on school nights and 15% of teens say they have fallen asleep during class. In the USA some schools are starting classes at 10 a.m. so that teens can get some extra sleep. These schools have noticed an improvement in their students' work.

Một số từ vựng:

- vital nutrients (n): dưỡng chất quan trọng

- diet (v/n): ăn uống theo chế độ, ăn kiêng

- properly (adv): đúng đắn, đúng cách

- fall asleep: buồn ngủ

According to the text, some schools in the USA have changed the starting time of lessons because ________.