Imagine that the U.S. is preparing for an outbreak of an unusual Asian disease that is expected to kill 600 people. Government officials have proposed two alternative programs to combat the disease. Under program A, 200 people will be saved. Under B, there is a one-third probability that 600 people will be saved and a two-thirds probability that nobody will. Confronted by this choice, 72 percent of people choose A, preferring to save 200 people for certain rather than risking saving no one.