Please answer with explanation

Suppose a company has recently relocated to new premises and decides to randomly assess their employee's opinion on the new premises. There are 150 employees in the company, divided into 10 different departments, with 5 employees per department. The managing director of the company decides to randomly select one department and asks each employee in that department to participate in an anonymous online survey. a) State the sampling method used by the managing director. b) Briefly explain why you chose that sampling method. c) The Chief Executive Officer (CEO) of the company has suggested that three departments should be selected and surveyed. Why do you think the CEO would suggest this