Researchers recently asked about attendance at religious services on a questionnaire completed by 74,534 women in the Nurses' Health Study who were free of cardiovascular disease and cancer at baseline. Twenty years later the researchers found that 13,537 of these women had died. Statistical analyses indicated that attendance at religious services more than once a week (as contrasted with never attending) signicantly predicted death when depressive symptoms, smoking, and optimism were controlled. That is, those three variables were controlled for statistically. The researchers concluded that physicians should recommend religion and spirituality as valuable health-related resources for all their patients. a. What type of study is this (e.g., correlational)? b. What are 2 strengths of this study and why are they strengths? c. What is 1 weakness of this study and why is it a problem? d. Given your answers to a-c, how would you evaluate the researchers' conclusions about their study