Mystery Shoppers Are People

Mystery shoppers are people

A) hired by a firm to get legal, though not necessarily ethical, information about competitive firms.
B) hired by a firm's employees to prove to the courts that a firm is using unfair labor practices.
C) hired by a customer to prove that illegal or unethical practices are regularly taking place at a particular establishment.
D) who pose as customers to check on the quality and pricing of a firm's products or services and are paid to write a detailed report on their experiences.
E) hired by law firms to check product safety.