Shelley sends Keats an offer via U.S. mail: "I offer to manage your website at a rate of $100 per hour. You must accept by Friday." Keats signs: "I accept, but I'll only pay you $90" and puts it in the mailbox on Friday. Shelley receives the letter Saturday. Which of the following is true?
I. A contract exists on the day Shelley sent the offer to Keats.
II. A contract exists as of Friday.
III. No contract exists because of the statute of frauds.
IV. No contract exists because of the mirror image rule.
-I only -I and III -I, II and IV -IV only -II only