Which of the following is an example of a reason why firms might pay efficiency wages ?

• A. At equilibrium wages workers sleep when the boss is not looking because workers are not deeply concerned about being fired
• B. At equilibrium wages workers often quit to find better jobs.
• C. At equilibrium wages only minimally qualified workers apply for the job
• D. At equilibrium wages, workers cannot afford a healthy diet so they fall asleep at work due to a lack of energy
• E. All of these answers