A survey by the Municipal Health Bureau found that in recent years, the number of adults with hepatitis B has increased year by year. However, the director of the Municipal Health Bureau said that it cannot be concluded that the incidence of hepatitis B is increasing year by year. Which of the following is true and best supports the Secretary's statement? ['The incidence of hepatitis B in adults is based on the results of several sample surveys conducted by the City Health Bureau.', 'Survey shows that hepatitis B cases among minors in AA city have dropped significantly.', 'In recent years, the incidence of hepatitis B in rural areas of city A has declined.', 'In recent years, more and more residents of city A have been vaccinated against hepatitis B.']