Best Trailers Inc. entered into a contract with Acme Cartage, for the sale of a new forty-foot (40') trailer. Best did not have the trailer in stock, so it notified Acme when it had the trailer in its possession. When notified by Best that the trailer was available at Best's lot, Acme indicated it would send a truck over to pick up the trailer. Best said it would keep the trailer inside the lot, which was locked and gated. Acme requested that the gate be left unlocked, as it would be picking up the trailer after 9:00 PM. Best demurred to leaving the gate unlocked, due to security issues, whereupon Acme indicated the trailer should be left outside the lot. When Acme arrived at 10:00 PM that evening, the trailer was nowhere to be found; it had been stolen. Acme demanded reimbursement from Best, which refused to do so. Who bears the risk of loss in this case, and why?