Sean submitted and Rene accepted a bid to supply approximately 4,000 tons of trap rock for an airport at a unit price. The parties executed a standard form of “Invitation, Bid, and Acceptance (Short From Contract)” supplied by Rene, including typed terms “to be delivered to project as required,” “delivery to start immediately,” and “cancellation by Rene may be effected at any time.” However, ___ requires that Rene orders and accepts the rock within a reasonable time unless Rene has given Sean a notice of intent to cancel.