Final answer:
A purchase requisition is usually authorized by the supervisor of the requisitioning department, who oversees the area needing goods or services. Purchasing managers or agents take over after approval, and customers do not have a role in internal approvals.
Step-by-step explanation:
Within the context of procurement and supply chain management, a purchase requisition is typically authorized by the supervisor of the requisitioning department. This implies that the responsibility mostly falls on the person in charge of the department that is initiating the request for goods or services. The role of the purchasing manager or purchasing agent often comes into play after the requisition is approved, where they handle negotiations with vendors and the actual procurement process. A customer would not authorize a purchase requisition within an organization, as their involvement is external to the company's internal procurement procedures.