5.5 Psychological response of firefighters. The Jour- nal of Human Stress (Summer 1987) reported on a study of "psychological response of firefighters to chemical fire." The researchers used multiple regression to predict emotional distress as a func- tion of the following independent variables. Identify each independent variable as quantitative or qual- itative. For qualitative variables, suggest several levels that might be observed. For quantitative vari- ables, give a range of values (levels) for which the variable might be observed.(a) Number of preincident psychological symptoms (b) Years of experience (c) Cigarette smoking behavior ((1) Level of social support (e) Marital status (f) Age