A study of 86 patients, all of whom suffered from disease T and received the same standard medical treatment, divided the patients into 2 equal groups. One group' s members all attended weekly support group meetings, but no one from the other group attended support group meetings. After 10 years, 41 patients from each group had died. Clearly, support group meetings do not help patients with disease T live longer. Which one of the following statements, if true, most seriously weakens the argument? ['The members of the group that attended weekly support group meetings lived 2 years longer, on average, than the members of the other group.', 'Some physicians have argued that attending weekly support group meetings gives patients less faith in the standard treatment for disease T.', 'Everyone in the group whose members attended weekly support group meetings reported after 1 year that those meetings had helped them to cope with the disease.', 'For many diseases, attending weekly support group meetings is part of the standard medical treatment.']