At Hamburger University, Workers Were Told to Vary Their Greetings

At Hamburger University, workers were told to vary their greetings to customers.Why?

A) This keeps the workers awake.
B) This constitutes a code to alert supervisors of potential problems.
C) This prevents the customer from seeing how routine the interaction is.
D) This cues the cooks about the order in which to prepare orders.
E) This reminds the customer to play the "customer's role."