Editorialist: Research reveals that patients of hospital cardiac units in which doctors perform many aggressive, high-tech procedures are less likely to be alive a month after leaving the hospital than are patients of hospital cardiac units that rely almost exclusively on standard treatments. This indicates that aggressive, high-tech treatments of cardiac disease are less effective than standard treatments. Which one of the following, if true, most weakens the editorialist's argument? ['Doctors who do not perform aggressive, high-tech procedures tend to place much emphasis on the prevention of cardiac problems through healthy lifestyle choices.', 'Patients with the most-severe cardiac problems tend to receive treatment at hospitals where many aggressive, high-tech treatments are performed.', 'All cardiac patients have access to hospitals in which relatively large numbers of aggressive, high-tech procedures are performed.', 'Some cardiac patients have lived for many years after receiving aggressive, high-tech treatments.']