For each scenario, determine the sampling method used by the managers from Exercise 2.
a) Use the company e-mail directory to contact 150 employees from among those employed for less than 5 years, 150 from among those employed for 5-10 years, and 150 from among those employed for more than 10 years.
b) Use the company e-mail directory to contact every 50th employee on the list.
c) Select several divisions of the company at random. Within each division, draw an SRS of employees to contact.