In October 2004, Xu Zhenjun set the marathon world record -- for running it backwards. How long did it take him?

• 3 hours, 43 minutes, 39 seconds
  Xu ran the 2004 Beijing Marathon backwards in 3 hours, 43 minutes and 39 seconds.
• 4 hours, 9 minutes, 34 seconds
  Xu ran the 2004 Beijing Marathon backwards in 3 hours, 43 minutes and 39 seconds.
• 13 hours, 44 minutes, 9 seconds
  Xu ran the 2004 Beijing Marathon backwards in 3 hours, 43 minutes and 39 seconds.