Mr. and Mrs. Brown go on a trip to Switzerland. While they are gone, Mr. Jones, their travel agent, sees in a newspaper: "Mr. Brown was killed in a ski accident." Mr. Jones immediately calls the police and says "Mrs. Brown killed her husband. Arrest her!"
The travel agent deduced that Mrs. Brown killed her husband because she bought only one ticket with a return flight back home. This ticket to Switzerland and back home again was for herself. For her husband, she bought only a one-way ticket to Switzerland.
Which deduction did the travel agent make? Click on 1 correct answer.