A、Its genetic advantage. B、Its cultural factors. C、Its better diet. D、Its universal health care. D短文中提到，尽管遗传因素和像饮食习惯之类的文化因素很自然地促

Beginning in the 1950s and 1960s, Japan began developing a reputation for its longevity. By the 1970s, the Japanese were the longest lived of any population in the world. Although genetic and cultural factors like diet certainly contributed to the long life span of the Japanese,(23)it was the country’s universal health care that was largely responsible for boosting quality of life and increasing the country’s life expectancy.(24)Even though Japan continues to have the highest life expectancy in the world, it is on track to be outpaced by other long-lived countries, like Sweden, Italy and Australia. Researchers believe that relatively high rates tobacco use, changes in diet and the rising rate of suicide are contributing to Japan’s slowing declines in rates of adult mortality. Physical illness is not the only drag on the country’s life expectancy: More than 30 000 Japanese people take their own lives each year, perhaps the continuing aftereffects of the 1997 financial crisis. Given the suicide rate’s close association with unemployment rates, it seems likely that this negative socioeconomic background is associated with the suicide trend in Japan.(25)Still, the biggest health challenge facing the Japanese is related to lifestyle factors like cigarette smoking, obesity and uncontrolled blood pressure—all of which contribute to chronic health problems that tax the public health care system. That system is already strained by the demands of an aging populace—23 % of the Japanese population is aged 65 years or older, a proportion that is projected to grow to 40% by 2050—and by injuries associated with recent natural disasters, such as the March 2011 earthquake.
23. What is the main reason for Japan’s long life span?
24. What do we learn about Japanese people today?
25. What is the most important factor that leads to Japanese health problems?