Herbed Wellness, a manufacturer of herbal products, wants its new headache remedy to be as effective as possible while using only natural ingredients. A controlled study has found that 58 percent of headache sufferers obtain complete headache relief from a dose of caffeine equivalent to that typically found in a cup of coffee. Therefore, even though the vast majority of its customers are health-conscious avoiders of coffee, Herbed Wellness should add caffeine to its new herbal headache treatment; doing so will prove both efficacious and cost-effective. The answer to which of the following questions would be most useful in evaluating the claim that caffeine will be efficacious in relieving headaches among Herbed Wellness customers?
A. Is the headache relief provided by caffeine as long-lasting as that provided by over-the-counter drugs such as aspirin?
B. What percentage of the study participants were regular coffee drinkers who suffer from caffeine-withdrawal headaches?
C. Is caffeine less expensive per dose than the individual herbs used in the headache formulation?
D. Does synthetic caffeine qualify as a natural substance?
E. What percentage of Herbed Wellness customers will shun the new headache remedy if it contains caffeine?