[单选题]标出主题句
Choose the best topic sentence from the group below by writing A, B, C or D.

本题考察主题句的特点。

主题句具有概括性。Mental symptoms of stress include anxiety, trouble sleeping and so on.意思是：心理压力的症状包括焦虑、失眠等等。

Symptoms of stress can vary widely from one person to the next. 意思是：压力的症状因人而异。

Some people may have headaches or back pain when they are under stress. 意思是：有些人在压力下可能会头痛或背痛。

Mental symptoms of stress can be controlled through drug therapy. 意思是： 心理压力可以通过药物治疗来控制症状。

ACD都是关于mental symptoms的具体方面，阐述的内容太过于具体，而B选项是从整体出发，更适合当做主题句。故选B。