参考答案

正确答案：B
解析：文章“Experts”部分中“But does a man who is a famous sportsman know more about these things than anyone else? And does he ever use the product he praises?”它后面那句告诉我们不应轻信明星，而应考虑他是否是他所做广告这一领域中的权威。所以答案为N。