In a Study to Determine the Least Amount of Time

In a study to determine the least amount of time necessary to clean an SUV while maintaining a high quality standard, the owner of a chain of car washes designed an experiment where 20
Employees were divided into four groups, each with five members. Each member of each group
Was assigned an SUV to clean within a certain time limit. The time limits for the groups were 20
Minutes, 25 minutes, 30 minutes, and 35 minutes. After the time limits for each group had expired,
The owner inspected each SUV and rated the quality of the cleaning job on a scale of 1 to 10. What
Are the factor levels for this study?

A) the quality ratings: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10
B) the number of employees in each group: 5
C) the number of groups: 4
D) the time limits: 20 min, 25 min, 30 min, 35 min