According to an effect first observed by Irving Fisher, government actors cannot simultaneously target both stable price levels and an arbitrary level of this quantity. If this quantity falls below the NAIRU level, an inflationary spiral may occur. In a steady-state economy, the Peter Diamond Coconut model predicts that a "natural" level of this quantity will occur. According to Okun's law, a 1 percentage point increase in this quantity is associated with a 2 percent drop in GDP. The Phillips curve plots this quantity against inflation. For 10 points, name this phenomenon that occurs when people are unable to find work.
a) Inflation
b) Unemployment
c) GDP
d) Interest Rates