【正确答案】 B

【答案解析】[听力原文]
   A study from the U.S. Centers for Disease Control and Prevention shows that most American children are physically unfit. But, children in other countries also face this problem.
   Health officials across the world are concerned about rising rates of obesity and type 2 diabetes in children as young as eight. This kind of diabetes is directly related to poor diet and lack of physical activity.
   The World Health Organization advises that children between the ages of 5 and 17 get at least 60 minutes of physical activity every day. The activity should be moderate to very energetic, or vigorous.
   Studies on children and exercise show that fitness is good for more than just physical health.
   A U.S. Institute of Medicine study shows that physical activity helps students with their studies.
   "The evidence is really emerging in the last five or six years. Both cognitive studies, as well as brain imaging studies and others, show the acute effects of physical activity on blood profusion in the brain. It really helps children learn, recall things faster, think faster and actually are more likely to achieve their full academic potential compared to children who are not physically active."
   What problem do most American children face according to the report?
此题问美国大部分儿童面临什么问题。新闻第一句直接提出“他们身体不健康”(physically unfit)。