A certain researcher is studying the effects of church affiliation and marital status on alcohol recovery. He reports a main effect for church affiliation. What does this mean?a. People who are married are more likely to recover from alcohol abuse. b. Whether or not a person goes to church will affect how well he recovers from alcohol abuse. c. Church attendance has no effect on alcohol abuse recovery. d. People who attend church will recover from alcohol abuse, but only if they are married.