In the Back-to-Back (B2B) Order to Cash flow, ordered items are purchased from a supplier. The Sourcing Rules have been defined for the item and the buy flow has been initiated. The sales order line is shown as Awaiting Shipping and the supply line status is `In Purchasing` with the supply order generated but the purchase requisition not generating. What is the reason? 

Answer options:

A. Work definition is missing for the item.
B. No Blanket Purchase Agreement (BPA) exists for this supplier " item combination.
C. The sourcing rule is incorrect.
D. ATP rule is not defined.

C