Yael Sent Jen an Offer to Sell His Mountain Bike

Yael sent Jen an offer to sell his mountain bike for $150.After thinking about the offer for a few days,Jen sent Yael a letter accepting his offer and asking if he intended to leave the book basket attached to the bike.The next day,before Jen's letter arrived,Yael phoned Jen and told her that he had decided to sell his bike to Jake,who had offered him $200.Which of the following statements hold true of this case?

A) Jen used unauthorized means of acceptance.
B) Jen's acceptance was good and a contract was created when Jens' letter was mailed.
C) Yael could revoke the contract as the goods had not exchanged hands yet.
D) The contract was not valid as the UCC held acceptances to be valid only when they were received and acknowledged in writing by the offeror.