In the Acquisition/payment Business Process, What Underlying Real Activity Does

In the acquisition/payment business process, what underlying real activity does the acquisition event represent?

A) The act of a department supervisor requesting the purchasing agent to purchase a type of good or service
B) The act of a purchasing agent placing an order with a vendor for goods or services
C) The act of a receiving clerk receiving goods or the act of an enterprise receiving services from a vendor
D) The act of an accounts payable clerk receiving a vendor invoice that summarizes the information about the goods or services the vendor claims to have sent
E) The act of a shipping clerk shipping goods to a supplier