Ambush marketing refers to the use of media and the public's attention to major events, and by holding events related to major events, they can associate themselves with major events, thereby attracting consumer associations and media attention. This type of marketing is usually hidden Suddenly, not appearing as a sponsor, but silently promoted his brand. According to the above definitions, which of the following is not ambush marketing? ['A mineral water company invites famous athletes to endorse it and puts advertisements in the prime time of TV media and video media of some large hotels.', 'After the earthquake, an outdoor company donated a tent worth 1 million yuan to the disaster area and held a donation ceremony.', 'A city held a knowledge competition for primary and secondary school students, a publishing group distributed its published books to participants for free.', 'From time to time during the Formula One World Championship, there will be people waving colorful flags printed with the trademark of a tire company.']