According to a study by the Centers for Disease Control and Prevention, tobacco use is the leading preventable cause of death, and 5 million people worldwide die from tobacco-related diseases each year. Among them, 600,000 die from second-hand smoke each year, and more than a quarter child. If the following are true, which one can most doubt the above viewpoint? ['More than 5 million people worldwide die each year from diseases caused by insufficient exercise.', 'More than 5 million people worldwide die each year from diseases caused by irregular lives.', 'Preventable causes of death of not less than 14.5 million people worldwide each year are not tobacco-related diseases.', 'Diseases caused by improper psychological adjustment each year become the primary preventable cause of death for human beings.']