Final answer:
The negative relationship between the inflation rate and the unemployment rate is known as the short-run Phillips curve, which indicates a tradeoff between inflation and unemployment in the short run. Option a is the answer.
Step-by-step explanation:
The negative relationship between the inflation rate and the unemployment rate is known as the A) short-run Phillips curve. This concept was first introduced from a Keynesian perspective, which indicated a tradeoff between inflation and unemployment in the short run due to the upward sloping short-run aggregate supply curve. Conversely, in the neoclassical viewpoint, the long-run aggregate supply curve is vertical, suggesting there is no long-term tradeoff between inflation and unemployment, leading to a vertical long-run Phillips curve. This curve remains at a consistent level of unemployment regardless of the inflation rate, given the economy's natural rate of unemployment.