Which of the following statements is correct?

A. There is clear evidence that unions have increased the average level of real wage rates for
all workers.
B. When fringe benefits are taken into account, the overall compensation of union and
nonunion workers is equal.
C. Approximately 10 percent of all work time is lost annually because of strikes.
D. There were 19 major work stoppages in the United States in 2011.

Answer: D