Questions 13 to 15 are based on the passage you have just heard.

Passage Two

    Most Americans don’t eat enough fruits, vegetables or whole grains. Researchers now says adding fiber to the teen diet may help lower the risk of breast cancer.

    Conversations about the benefits of fiber are probably more common in nursing homes than high schools. But along comes a new study that could change that. Kristi King, a diet specialist at Texas Children’s Hospital finds it’s hard to get teenager patients’ attention about healthy eating but telling them that eating lots of high-fiber foods could reduce the risk of breast cancer before middle age. That’s a powerful message.

    The new finding is based on a study of 44,000 women. They were surveyed about their diets during high school, and their eating habits were tracked for two decades. It turns out that those who consumed the highest levels of fiber during adolescence had a lower risk of developing breast cancer, compared to the women who ate the least fiber. This important study demonstrates that the more fiber you eat during your high school years, the lower your risk is in developing breast cancer in later life.

    The finding points to long-standing evidence that fiber may reduce circulating female hormone levels, which could explain the reduced risk. The bottom line here is the more fiber you eat, perhaps, a lower level of hormone in your body, and therefore, a lower lifetime risk of developing breast cancer. High-fiber diets are also linked to a reduced risk of heart disease and diabetes. That’s why women are told to eat 25 grams a fiber a day—men even more.

15. What explanation does the speaker offer for the research finding?

解析：A。本题目为细节题。问题为：关于在青少年的饮食中增加膳食纤维的最新研究告诉了我们什么？原文所在句：The bottom line here is the more fiber you eat, perhaps, a lower level of hormone in your body, and therefore, a lower lifetime risk of developing breast cancer.可见，简言之，吃得纤维越多，身体中的激素水平越低，因此一生中患乳腺癌的风险就越低。故正确答案为A）Fiber may help to reduce hormones in the body。