The restriction enzyme Scs1 cuts at a restriction site that is found only very rarely in dog genomes. One dog, Jimmy, has two restriction sites for this restriction enzyme in his genome. Another dog, Billy, has three restriction sites for this enzyme in his genome. For this problem assume there is only one chromosome in dogs.

One of these dogs ate some of a birthday cake. Digestion and electrophoresis of DNA found at the scene of the crime with the restriction enzyme Scs1 revealed a banding pattern comprised of four bands. Which dog was most likely not responsible for eating the cake? Why?