A rehabilitation center researcher was interested in examining the relationship between physical fitness prior to surgery of persons undergoing corrective knee surgery and the time required in physical therapy until successful rehabilitation. Data on the number of days required for successful completion of physical therapy and the prior physical fitness status (below average,average, above average) were collected.a. Based on this dataset, identify the response variable, factor, factor levels, treatments, and the experimental unit of study.b.Is this study an experimental or observational? Explain.