(2 points) A group of college students believes that herbal tea has remarkable restorative powers. To test their theory, they make weekly visits to a local nursing home, visiting with residents, talking with them, and serving them herbal tea. After several months, many of the residents are more cheerful and healthy. (a) The lurking variable in this experiment is A. the fact that this is a local nursing home. B. herbal tea. C. visits of the college students. D. the emotional state of the residents. (b) The explanatory variable in this experiment is A. visits of the college students. B. the fact that this is a local nursing home. C. herbal tea. D. the emotional state of the residents. (c) Which of the following may be correctly concluded from this study