Okun's law states that
a. when growth of gdp is positive, it tends to be positive in subsequent quarters.
b. when growth in real gdp is above 3%, unemployment drops and when it is below 3%, unemployment increases.
c. during recessions, firms tend to not lay off workers if they believe the slowdown will be temporary.
d. when growth in real gdp is below 3%, unemployment drops and when it is above 3%, unemployment increases.