Which of the Following Is Correct? the Natural Rate of Unemployment

Multiple Choice

Which of the following is correct? The natural rate of unemployment

A) is a zero unemployment rate.
B) has been steady at 3 percent over the past decade.
C) is defined by Friedman as that rate of unemployment "in which everyone who wants a job can have a job."
D) is the unemployment rate that exists in the long-run.
E) None of the above