Anna placed an advertisement in a newspaper that said: "Five goldfish for sale. $2 each. First come/first served. Please respond in person or by email to A..a@nryerson.ca." Nick saw the advertisement and immediately sent an email message that said: "I will pay $10 for the five goldfish." However, when Nick arrived at Anna's door with the cash in hand, she refused to hand over the goldfish. She explained that while Nick's message was the only reply that she had received in response to her advertisement, she had changed her mind and had decided to keep the kittens for herself. Provide an argument on behalf of Nick that would support the creation of a contract with Anna.