Answer:
Vince and Sun-Hi's Book
With Sun-Hi's delivery of the book, the offer by Vince is accepted by Sun-Hi.
Acceptance of an offer is necessary to make a contract.
Explanation:
An offer by Vince is not a contract, but its acceptance by Sun-Hi without a counter-offer makes it a valid contract that can be enforced in law if other ingredients for a valid contract are present. Acceptance establishes the agreement between Vince and Sun-Hi. Once Sun-Hi accepts Vince's offer with valid considerations (the book and double the price), the agreement for a business transaction between them is consummated. It is acceptance that completes the exchange of promises in this simple contract.
