In which of the following functions is source determination available?

Source determination is a function used in procurement processes to identify suitable suppliers for purchasing requirements. The ability to determine sources is crucial in streamlining procurement and ensuring that the organization can effectively source materials from appropriate vendors.

In the context of the options provided, assigning and processing purchase requisitions is where source determination plays a pivotal role. When a purchase requisition is created, the system performs a source determination process to identify which vendors are available to fulfill the request. This process includes evaluating factors like the vendor's price, availability, past performance, and other criteria configured in the system.

In contrast, maintaining a quote from an RFQ, creating a contract release order, and converting a planned order into a purchase requisition involve processes that do not inherently require the identification of new sources at their initiation. Instead, these functions might rely on agreements or existing data rather than actively determining new sourcing options.

Thus, the function of assigning and processing purchase requisitions is directly tied to source determination, allowing the procurement team to find the most suitable suppliers before moving forward with actual purchase orders.