Anna promises to sell Bert Lot C for $200,000. They agree Bert will transfer $100,000 on February 10, 2021, and $100,00 on March 10, 2021, to Anna to satisfy the payment. They are friends and neighbors, so they discuss the deal casually and never put it in writing. On February 10, 2021, Bert transfers $100,000 to Anna’s bank account as they had previously discussed. A couple of days later, Anna calls Bert and tells him that she has another buyer who will pay $250,000. What are Bert's rights