Final answer:
Credit for returned erroneously ordered parts is generally determined on a case-by-case basis, considering factors like the return policy, nature of the parts, and purchasing agreement.
Step-by-step explanation:
When erroneously ordered parts are returned to supply, the method for distributing credit is generally D) determined case by case. Each situation may have different circumstances regarding the ordering error. It could depend on the supplier's return policy, whether the parts were custom-made, the reason for the error, or the conditions of the purchasing agreement. These factors influence how the credit, if any, is allocated. It is not typically distributed among personnel or based solely on demand processing efficiency.