In winter, a city's bus system added temporary buses on many lines to supplement bus transportation on these lines, but the phenomenon of crowding passengers on the original line has not been alleviated for a period of time. In the following statements, what does not help explain the above phenomenon? ['Of the passengers on these routes, a sudden increase in the number of migrant workers in the winter.', 'For a period of time, people have no idea about the stop and operating time of newly added temporary buses.', 'The number of temporary buses increased during the daily peak hours.', 'The driver conductor of the temporary bus has signed a contract with the company.']