A、It reduces the work burden of your heart and blood vessels. B、It makes your heart and blood vessels work too hard. C、It reduce

(22)Today, we will talk about the effect of Internet on our daily life and the related research on it.
   The Internet plays a big part in human life. We use it for work and entertainment. We can find new recipes on the Internet. We can use it to learn a new language. We use the Internet to connect with family and friends and stay in touch with issues we care about. The list goes on and on. In one word, there may be no going-back to an Internet-free life.
   But using Internet too much may be bad for our health. A new study finds that heavy Internet use may be connected to high blood pressure in an unlikely group—the teenagers. The study results show that teens who spend at least 14 hours a week online are more likely to have high blood pressure. (23) High blood pressure makes your heart and blood vessels work too hard. Over time, this extra strain increases your risk of a heart attack or a stroke. It can also cause heart and kidney diseases.
   The Henry Ford Hospital in Detroit did the study. It involved 335 young people, from 14 to 17 years old. One hundred and thirty-four of the teens were described as "heavy Internet users. " (24)Researchers found that out of these 134 teens, 26 had high blood pressure. The researchers say the study is the first to connect heavy web use with high blood pressure. Other research has connected heavy Internet use with health problems including anxiety, depression and obesity.
   (25)Andrea Cassidy, the lead researcher of the study, said that "using Internet is part of our daily life but it shouldn’t consume us." She adds that it is important for teens to take "regular breaks from their computers or smart phones" and to do "some kind of physical activity." She suggests that parents limit their children’s use of the Internet to two hours a day, five days a week.
   The Centers for Disease Control and Prevention says, 70 million, or 29%, of American adults have high blood pressure. Just more than half of those people have taken steps to control it. The CDC estimates that high blood pressure costs the United States $46 billion each year.
Questions 22 to 25 are based on the recording you have just heard.
22. What is the focus of the speech?
23. What effect may high blood pressure have on the teenagers?
24. What can we learn about the study by Henry Ford Hospital in Detroit?
25. What does Andrea Cassidy suggest teens should do in daily life?