单项选择题

In this section you will hear everything ONCE ONLY. Listen carefully and then answer the questions that follow. Mark the best answer to each question on ANSWER SHEET TWO.
The reasons why most people have trouble sleeping are all of the following EXCEPT that they ______.

A. are too busy working
B. aren’t aware of the importance of sleep
C. have some health problems
D. don’t think sleep can influence health