Invisible implantation: refers to publicity strategies that make audiences unknowingly affected through peripheral information, symbol systems, and other unobservable forms. Which of the following is invisible implants. ["In a TV series, all characters use the same brand of mobile phone, and use the brand's classic ringtones.", 'Before the arrival of the City Games, the merchants successively put various cultural and creative products with the emblem of the City Games on the counter.', 'In the collection of the museum logo design in a certain city, the plan No.8 attracted the attention of the judges with its strong regional cultural elements.', 'The wedding anniversary is approaching. In order to remind the careless and busy husband, Xiaoli secretly replaced his mobile phone screensaver with a wedding photo.']