When Does the Unemployment Rate Increase

Multiple Choice

When does the unemployment rate increase?  

A)  It increases whenever the number of persons classified as unemployed increases. 
B)  It increases whenever the number of unemployed increases relative to the size of the labour force. 
C)  It increases whenever the size of the labour force decreases. 
D)  It increases whenever the size of the labour force decreases and the number of unemployed decreases.