Mary Green, who works as a manager at the Sea Breeze Restaurant, is analyzing service problems that are increasingly causing owners' concerns. She found out that the customers often decline the menu items ordered because they don't like the substitutes for traditional ingredients, for example, they decline chicken dishes advertised as made from chicken breast but made from chicken thighs instead. The returns of well-prepared dishes to the kitchen increase waste and, therefore, cut into profits. Which of the following control points is likely to be the focus of the initial corrective action? a. Purchasing of food b. Issuing of food c. Preparing of food d. Serving of food