Jennifer Lopez owned four speedboats named Porpoise, Priscilla, Providence, and Prudence.  On April 2, Jennifer made written offers to sell the four boats in the order named for $4,200 each to Aiden, Knox, Becca and William, respectively, allowing ten days for acceptance.  In which, if any, of the following four situations described was a contract formed?

• Five days later, Aiden received notice from Jennifer Lopez that she had contracted to sell Porpoise to another buyer, Ben. The next day, April 8, Aiden notified Jennifer Lopez that he accepted Jennifer Lopez's offer.
• On the third day, April 5, Knox mailed a rejection to which reached Jennifer Lopez on the morning of the fifth day. But at 10:00 A.M. on the fourth day, Knox sent an acceptance by telegram to Jennifer Lopez, that she received at 12:00pm on the same day, that he had accepted her offer.
• Becca, on April 3, replied that she was interested in buying Providence but declared the price asked appeared slightly excessive and wondered if, perhaps, Jennifer Lopez would be willing to sell the boat for $3,900. Five days later, having received no reply from Jennifer, Becca, by letter, accepted Jennifer's offer and enclosed a certified check for $4,200.
• William was accidentally killed in an automobile accident on April 9, the following day, the executor of William's estate mailed Jennifer an acceptance of her offer.