American attitudes tend to be rather insular, but there is much we can learn from other countries. In Japan, for example, workers set aside some time each day to exercise. And many of the corporations provide elaborate exercise facilities for their employees. Few American corporations have such exercise programs. Studies have shown that the Japanese worker is more productive and healthier than the American worker. It must be concluded that the productivity of American workers will lag behind their Japanese counterparts, until mandatory exercise programs are introduced. The argument presented in the passage depends on the assumption that: A. even if exercise programs do not increase productivity, they will improve the American worker's health. B. the productivity of all workers can be increased by exercise. C. exercise is an essential factor in the Japanese worker's superior productivity. D. American workers can adapt to the longer Japanese workweek.