All of the Following Except One Are Valid Explanations of Why

Multiple Choice

All of the following except one are valid explanations of why the natural rate of unemployment is now higher than it was twenty-five years ago.Which is the exception?

A) Wage rates are now much higher than they were in the past.
B) Unemployment benefits are higher than in the past.
C) People are taking longer to search for a new job.
D) More females are participating in the labour force than in the past.