Which one of the following statements regarding physical activity and arthritis is most accurate? a. intense physical activity has been shown to increase the risk of arthritis in individuals over age 50. b. post-menopausal women should not engage in physical activity due to the increased risk it places on them to develop arthritis. c. moderate exercise reduces swelling in joints and relieves pain associated with arthritis. d. individuals who begin to exercise at a younger age are more susceptible to arthritic conditions in adulthood than those who do not.