In which of these experiments is coffee the dependent variable? Select a Choice Below current question choices OptionA One, two, or three cups of coffee are given to subjects in a hospital waiting room to measure heart rates after caffeine. OptionB Regular and decaffeinated coffee in various amounts are given to adults with ADHD to compare observational characteristics of restlessness. OptionC After a marketing campaign emphasizing some new flavors of coffee, the pounds of coffee purchased in the community are recorded. OptionD Laboratory mice are given several different strengths of caffeine in coffee to determine carcinogenic effects