Which of the Following Is Not a Reason Why Unionized

Which of the following is not a reason why unionized firms can successfully compete with nonunionized firms?

A) Employee morale may be higher at unionized firms, so workers are more productive.
B) Communication between management and workers is better at unionized firms.
C) Labor turnover is lower at unionized firms, so unionized firms have lower hiring costs.
D) Unionized firms are legally protected from price competition with nonunionized firms.