Differential pricing: refers to enterprises that use different prices for the same product produced by the enterprise according to different markets and different customers. Which of the following does not belong to differential pricing? ['Tourist attractions: 20% off for senior citizens, 30% off for children, 50% off for student tickets, full tickets for general customers.', '2-degree liquor produced by a winery at a wholesale price of 102 yuan per bottle and a retail price of 128 yuan per bottle.', 'Electricity company adopts time-sharing pricing for residential electricity, 0.9 yuan per kilo from 6: 00 to 12: 00, 1.5 yuan per kilo from 12: 00 to 24: 00, 0.3 yuan per kilo from 0: 00 to 6: 00.', 'GB of memory for a certain brand of mobile phone costs 4888 yuan, 1688 yuan for 5388 yuan, 32GB 6288 yuan.']