Mr. D is the manager of a local walgreens. His biggest concern is to make sure that his store is always making the most profit possible. He cuts costs by focusing on certain logistical decisions. Every other day walgreens receives shipments from pepsi, evian, hershey, and numerous other manufacturers. Walgreens insists on small shipments every two days, which helps to keep their inventory costs low. What system is mr. D using at walgreens to reduce his costs?.