Procurement involves the acquisition of needed materials$/$supplies from vendors. The process is as follows: $(1)$ the warehouse sends a purchase requisition to the purchasing department; $(2)$ the purchasing department creates a purchase order and sends it to the vendor; $(3)$ the vendor receives the purchase order and ships the materials to the warehouse $(4)$ the vendor sends the invoice to the accounting department; $(5)$ the ascounting department sends payments to the vendor; This is an example of $a$ :

A$)$ Business process

B$)$ Business process improvment

C$)$ Cross$-$functional business process

D$)$ Business process reengineering