Estrella and Mishkin (1996) developed a somewhat successful model to predict whether the economy is going into recession using what variable? 1) spread between the 10-year U.S. Treasury Inflation Protected Security and the 3-month T-Bill. 2) spread between the 5-year U.S. Treasury Note and the 3-month T-Bill. 3) spread between the 10-year U.S. Treasury Note and the 3-month T-Bill. 4) spread between the 30-year U.S. Treasury Note and the 3-month T-Bill.