[解析]
(1)D 主旨大意题。根据主题句 Jeans are very popular all over the world.牛仔裤在全世界很受欢迎。以及后文讲述牛仔裤的历史可知短文在谈论"牛仔裤",故选D。
(2)A 细节理解题。根据The company was founded(建立) in 1853 by 24-year-old Levi Strauss.Twenty years later,he made first blue jeans in the world.建立公司时Levi Strauss24岁,20年后生产第一天牛仔裤,即24岁时,故选A。
(3)A 细节理解题。根据it's often not right to wear jeans in formal(正式的) places在正式场合穿牛仔裤通常是不对的,可知参加重要会议是正式场合,最好不穿牛仔裤,故选A。