Apples Inc. is a wholesale company in Florida that sells apples to retail grocery stores throughout the Southeast United States. Recently, Apples Inc. has had an excess supply of apples and needs to dispose of its inventory as quickly as possible due to the perishable nature of the apples. To reduce its inventory, the sales force Apples Inc. calls its grocery store customers and offers to sell apples immediately for delivery, and the wholesale price is $500 per ton (which is about $300 less than the usual price). Apples Inc. does not explicitly put a limit on how long the offer is available.

How long does this offer remain open? Explain the law.