Yasmin Offers to Landscape Bert's Property for $2,000

Yasmin offers to landscape Bert's property for $2,000.Two days after making the offer,Yasmin changes her mind and mails Bert a letter revoking her offer.The next day,Bert,who has not received Yasmin's letter,calls Yasmin and accepts her offer.Does a contract exist?

A) No,because Yasmin mailed her revocation before Bert's acceptance.
B) No,because Yasmin can revoke her offer at any time.
C) Yes,because Bert was not notified of Yasmin's revocation at the time he accepted.
D) Yes,because mail is not a proper method of revoking an offer.