To help the Professor's dog Shaun learn to fetch, Wandas Pet Supplies Inc. has invented a new ball that automatically comes back to the thrower even if the dog gets distracted and ignores the ball. At noon each day, Wanda's Pet Supplies production manager prepares a purchase requisition for items needed. The Purchasing Department manager reviews this requisition and checks to see if the items are already on order. If the items are not already on order, the Purchasing Department manager updates the purchase order file to generate the appropriate purchase orders and forwards them electronically to the appropriate vendors. If the items were already on order, the Purchasing Department manager emails the production manager with an update on when the ordered items will be received. When the vendor ships the ordered goods, the warehouse department employees verify that the goods received were actually ordered. If the warehouse employee discovers discrepancies between the items received and the items ordered, the warehouse employee updates the discrepancy file. If the items received match the order of the item, the warehouse employee updates the receiving report file. The expenditure system generates Weekly Purchase Report based on the purchase order file which is forwarded to Wanda's Pet Supplies Inc. owner, Wanda.

a. Prepare a context/overview DFD b. Prepare a level 0 DFD c. Prepare a process map