For which of the following transactions can the source of supply be determined automatically?

In the context of SAP Materials Management, the determination of the source of supply relates to how the system identifies potential vendors or suppliers to fulfill a procurement need.

When creating a purchase order with an unknown vendor, SAP can utilize various criteria and regulations set within the enterprise's procurement process to automatically suggest sources of supply. This could involve checking the existing material master data, vendor master records, contract agreements, and other relevant procurement information. Thus, the system can suggest the most suitable vendors based on predefined parameters without requiring prior knowledge of which vendor will be used.

Creating a purchase order with a known vendor typically does not involve automatic determination, as the vendor is already specified. Likewise, while creating a reservation or a purchase requisition, the focus tends to be on managing inventory and requesting materials, rather than automatically suggesting suppliers.

Therefore, the ability to automatically determine a source of supply is best exemplified in situations where the vendor is not predetermined, allowing the system to search for and suggest potential vendors based on the criteria available.