下列对声现象的描述，应用物理知识解释正确的是

阅读理解

Everybody wants to be healthy. You know food is very important. There are lots of healthy food. You can have more bananas, apples, oranges, tomatoes and lettuce because fruit and vegetables are good for you. But don’t eat too much chocolate. It’s not healthy food. Healthy food can make you grow (生长) and make you strong（强壮的） and happy. Remember there is a saying—“An apple a day keeps the doctor away（远离）”. Sports can also keep you healthy. Get up early and do some sports every day. Don’t be lazy（懒惰的）. You will be healthy and happy.