17. Sixty patients with arthritis are randomly divided into two groups. One group is given exercises to do on a daily basis. The other group is given medication to take daily. After one year, the group who did the daily exercises had a lower rate of pain. Choose the correct terms for they type of study, the explanatory variable and the response variable a. observational, medication/exercise, reduction in pain b. experimental, medication/exercise, reduction in pain c. observational, reduction in pain, medication/exercise, d. experimental, reduction in pain, medication/exercise