'A' makes a proposal to 'B' by post. But 'B' dies before the letter of offer reaches 'B'. 'B''s son accepts the proposal. Which of the following statements is most appropriate regarding the liability of 'A'?

• A. 'A' is liable because the offer has been accepted by the son of 'B'
• B. 'A' is not liable because 'B' could not accept because of his death
• C. 'A' is liable because he did not reject the acceptance made by the son of 'B'
• D. 'A' is not liable as the offer can be accepted only by the person to whom the offer is made