2. A researcher wants to examine if the amount of sleep affects students' time to complete a puzzle task. The researcher recruited 60 college students and divided them into four different sleep groups: 2 hours, 4 hours, 6 hours, and 8 hours. The next day, the researcher asked all participants to complete a puzzle task (each puzzle was equal difficulty). Their time was recorded (in seconds) how long it took each participant to finish the puzzle task. (1 point each) a. Identify the independent variable. b. What are the levels of the independent variable? c. Is the independent variable qualitative or quantitative? d. Identify the dependent variable. e. What scale of measurement is utilized for this set of data collected by the researcher (ordinal, ratio, nominal, or interval)