Which one of the following statement is incorrect?
Select one:
a. A structural change in the economy would imply a change in the cyclical unemployment rate.
b. The natural unemployment rate would prevail if the economy were neither in recession or boom.
c. The current (observed) unemployment rate is the sum of the natural and cyclical unemployment rate
d. The cyclical unemployment rate is associated with short-run fluctuations
e. The natural rate of unemployment does not change over time