Which of the following best describes varicose veins? a. veins cannot prevent the backflow of blood. b. veins lose the ability to transport blood to the heart. c. veins become used for transporting blood to and from the heart. d. veins become less efficient at transferring waste to the blood.

Which of the following represents the results of a review of well-controlled studies of vitamin c supplementation on the resistance to, and recovery from, colds? there was a reduction in the duration of colds by 50% on the average. there was a slight effect on reducing the duration and severity of colds for people taking vitamin c supplements. there was a significant reduction in the duration of colds in people who consumed at least one gram a day. there was a significant reduction in the number of colds only in people who consumed > three grams per day.