"Fat Man and Little Boy" is the fifth episode of which sixteenth season that began on Sunday, November 7, 2004 and contained 21 episodes, beginning with Treehouse of Horror XV? 
The Simpsons (season 16): "The Simpsons"' sixteenth season (November 7, 2004 - May 15, 2005) began on Sunday, November 7, 2004 and contained 21 episodes, beginning with Treehouse of Horror XV.
i don't know