In a research project intended to gather data on the effects of type of study method on examination performance, subjects are randomly assigned to one of two conditions. In one condition, they study alone, using notes they took during class lectures. In a second condition, subjects study in interactive groups with notes from class lectures. The amount of time spent studying is held constant. All students then take the same exam. In this study: a. What is the independent variable? b. What is the dependent variable?.-- c. Identify the control and experimental groups. . d. Is the independent variable manipulated? or is it a participant variable?