Which of the following statements is incorrect? a. The HP filter is a standard technique in macroeconomics for separating the long-term trend in a data series from short-term fluctuations associated with business cycles. b. Historically, major causes of the US recessions include industrial shocks, oil price shocks, inflationary overheating (that leads the Fed to aggressively raise interest rates), and financial imbalances and asset price crashes. c. Financial risk has been the key source of recessions in recent past. d. In recent years, a flatter and more anchored Phillips curve relationship between inflation and unemployment has reduced the risk of inflationary overheating. e. None of the above are incorrect