Management at a retail store is concerned about the possibility of drug abuse by people who work there. They decide to check on the extent of the problem by having a random sample of the employees undergo a drug test. Several plans for choosing the sample are proposed. Name the sampling strategy in each.(4 points)

a.Randomly select an employee shift and test all the people who work during that shift.

b.Choose the fourth person that arrives to work for each shift.

c.There are four employee classifications: supervisors, full-time clerks, part-time clerks, and maintenance staff. Randomly select ten people from each category.

d.Each employee has a three-digit identification number. Randomly choose 40 numbers.