Rudy puts this poster, with a photo of his dog, on utility poles around his neighborhood: "$50 reward for the return of my lost dog." Carlene doesn't see the poster, but she finds the dog and, after looking at the tag on its collar, returns the dog to Rudy. As she leaves his house, her eye falls on one of the posters, but Rudy declines to pay her anything. Why is Rudy correct that Carlene has no legal right to the reward?