On 2 May, Boston Technology Ltd Receives a Letter from Calculatrix

On 2 May, Boston Technology Ltd receives a letter from Calculatrix Co offering 250 calculators for £7000. On 10 May, Boston Technology sends a letter to Calculatrix in which they accept the offer. This letter reaches Calculatrix on 12 May. On the evening of 7 May, Calculatrix realizes that they have made a miscalculation and that the offer should have been 250 calculators for £7500. On 8 May, Calculatrix sends Boston Technology a letter revoking the offer. Because of the weekend break, this letter only arrives on 11 May. Has there been a contract concluded between the parties? If so, on what date; if not, when was the offer revoked?

A) No, the offer was revoked on 8 May.
B) Yes, the offer was accepted on 10 May.
C) No, the offer was revoked on 11 May and Boston Technology's acceptance only reached Calculatrix on 12 May.
D) Yes, the offer was accepted on 12 May.