Final answer:
The Requisitioning Activity Code in a due-in document is what identifies the base that placed the requisition, distinguishing it from other parts of the document like the Ship-to Address, Document Identifier Code, and Requesting Office Code. So, the correct answer is option b.
Step-by-step explanation:
The part of the due-in document that identifies the base that placed the requisition is the Requisitioning Activity Code. This code is specific to the entity requesting the items and is essential for ensuring that the supplies are sent to the correct location.
Other parts of the due-in document, like the Ship-to Address, Document Identifier Code, and Requesting Office Code, provide additional but distinct information.
The Ship-to Address specifies the destination for delivery, the Document Identifier Code categorizes the type of requisition or order, and the Requesting Office Code could indicate details about the office within an organization that made the request.