单选题

Which of the following is TRUE?

A If you have breakfast every morning, you’ll be fat

B All the traffic accidents are caused by poor sleep

C To join a social group helps you have a healthy mind

D Having a hobby is the best way to relax

解析：
由原文第四个小标题Join social groups中的描述“Also，being in a group keeps your mind busy. An active mind is a healthy mind”可知，C项“加入社团可以让你拥有健康的心态”正确。原文第一个小标题中提到“if you eat a meal in the morning you may not become too fat”，故A项与原文意思相反，故要排除。B项“所有的交通事故都是由睡眠质量差造成的”过于绝对，故也要排除。原文结尾处提到“Hobbies help people to relax and rest.”，但并没有说有一项爱好是最好的休息方式，故D项属于过度推断，也应排除。