Among the Following Relationship Cases, Select the Customer-Supplier Relationship You

Among the following relationship cases, select the customer-supplier relationship you think is the healthiest.

A) The customer is closely integrated with the systems of a supplier who deals in commodities.
B) The customer involves the supplier of a core component in its product design process.
C) The customer uses its information gathered from closely working with an important supplier to reduce the supplier's selling price.
D) The customer frequently uses reverse auctions in most of their purchase decisions.