explain why in a paragraph

A supply manager is negotiating a contract with a supplier who will be supplying a critical product with multiple development and production milestones. Which of the following would be the MOST effective method for the supply manager to ensure that the product is completed and delivered according to schedule? A. Negotiate a strong cancellation provision in case the supplier fails to meet the schedule. B. Establish a solid annual work plan that lists the required tasks. C. Develop a workable backup plan in the event the supplier fails to meet the schedule. D. Require the supplier to submit progress reports that show the supplier's progress against each milestone