how can do IRAC answer for the following question

On Monday, Constance advertised in a local newspaper that she would pay a reward of $1,000 to the person who found her pet dog, Buddy. Constance had lost Buddy when she had taken him for a walk at the park. Buddy was frightened by some children and ran away. On Thursday, Christopher, while going for a run, found Buddy. Christopher knew that the dog belonged to Constance because he had seen her with the dog many times. He took Buddy to Constance who was delighted that her dog was back with her. She invited Christopher to lunch to thank him for finding her dog. On Friday, Christopher saw the advertisement in the local newspaper. He went back to Constance to ask for the reward for finding her dog. Constance however refused to pay anything.

Advise Christopher if he is entitled to the reward.