Read the following excerpt from Levitt and Dubner’s Freakonomics.So what do the bagel data have to say? In recent years, there have been two noteworthy trends in the overall payment rate. The first was a long, slow decline that began in 1992. By the summer of 2001, the overall rate had slipped to about 87 percent. But immediately after September 11 of that year the rate spiked a full 2 percent and hasn’t slipped much since. (If a 2 percent gain in payment doesn’t sound like much, think of it this way: the nonpayment rate fell from 13 to 11 percent, which amounts to a 15 percent decline in theft.) Because many of Feldman’s customers are affiliated with national security, there may have been a patriotic element to the 9/11 Effect. Or it may have represented a more general surge in empathy.The excerpt serves as which type of support for the authors’ argument?