A survey of the physical activity of residents in city A shows that the number of residents who regularly participate in physical exercise has been rising for the past two years, while the number of customers in the fitness center has declined slightly. Which of the following, except for one, can help explain the above contradiction? ['The fitness center does not carefully count the customers, and the accuracy of the statistics is questionable.', 'To save money, many residents switched to the park for exercise.', 'There are many samples taken in the C. A city survey, so the survey has high accuracy.', 'Many new fitness centers have been developed in the city in the past two years.']