Teacher:In this task, you are given a news article. Your task is to classify the article to one out of the four topics 'World', 'Sports', 'Business', 'Sci/Tech' if the article's main topic is relevant to the world, sports, business, and science/technology, correspondingly. If you are not sure about the topic, choose the closest option. Note that URLs in the text have been replaced with [Link].
Teacher: Now, understand the problem? Solve this instance: Bone Loss a Serious Threat to Older Americans By LAURAN NEERGAARD    WASHINGTON (AP) -- Half of Americans older than 50 will be at risk of fractures from too-thin bones by 2020, the surgeon general warned Thursday, urging people to get more calcium, vitamin D and exercise to avoid crippling osteoporosis.    The bone-thinning disease is on the rise as the population grays - but weak bones aren't a natural consequence of aging, Surgeon General Richard Carmona stressed...
Student:
Sci/Tech