Epstein compared "feelings of fear and anxiety" of experienced parachutists (more than 100 jumps) to those of novices (fewer than 10 jumps). Feelings were measured on a questionnaire with scores from 1 (calm) to 10 (very nervous). The subjects were all men in their 20s. Identify: a. the dependent variable b. the independent variable, and the names of the levels c. a controlled extraneous variable d. a quantitative variable e. a categorical variable