1. A research team is interested in examining the effects of caffeine consumption on sleep quality in first-year medical school students who report consuming caffeine. Before designing their study, the research team reviewed the relevant literature. Prior theory, namely the adenosine receptor theory, suggests that caffeine blocks adenosine receptors in the brain, which can interfere with the sleep-wake cycle and negatively impact sleep quality. Prior empirical research has shown that caffeine has a stimulating effect on the central nervous system, leading to increased alertness and difficulty falling asleep or maintaining sleep. The research team recruits 50 first-year medical school students who report consuming caffeine daily to be in their study and categorizes them into two groups based on their self-reported caffeine consumption habits. Group A consists of students who report consuming high levels of caffeine on a daily basis (more than 400mg per day), while Group B consists of students who consume low levels of caffeine on a daily basis (more than Omg but less than 50mg per day). The research team collects data on sleep quality by asking participants in both groups to rate their sleep quality on a scale of 1-8 (with 1 representing extremely poor sleep quality and 8 representing excellent sleep quality). a. What kind of research method (experimental or non-experimental) was used in this study? Briefly explain your answer. b. What is the population and sample? c. What is a research hypothesis for this study? d. What is the independent variable or quasi-independent variable? e. What is the dependent variable? f. What is the scale of measurement of the dependent variable? Briefly explain your answer.