A. Describe the following graphical techniques that system analysts use to describe an information system. (a) Use Case Diagram (b) Sequence Diagram (4 Marks) B. Pustaka Jaya Berhad (PJB) is one of the main book dealers in Northern Malaysia. It has been in operation since 1967. The branches are located at Kangar, Alor Setar and Sungai Petani. The following narrative describes the purchase processing activities at PJB. The purchases process begins with the purchasing agent, who monitors the level of books available via a computer terminal listing current inventory. Upon noticing deficiencies in inventory levels, the agent generates three copies of purchase order: one is sent to accounts payable, one is sent to the vendor and one is sent to the receiving department. Vendors will generally ship the products within five business days of the order. When goods arrive in the receiving department, the corresponding bill of lading and packing slip always accompany them. The receiving department clerk unloads the goods and then reconciles the packing slip with the purchase order. After unloading the goods, the clerk prepares a receiving report and sends one copy together with the goods to the warehouse, and another is sent to the accounts payable department. In the warehouse, the copy is simply filed once the goods are stored on the shelves. When the accounts payable department receives the purchase order and the receiving report, the documents are temporarily filed until the respective invoice arrives from the vendor. Upon receipt of the invoice, the accounts payable clerk removes the purchase order and the receiving report from the temporary file and reconciles them with the vendor's invoice. The clerk then manually records the liability in the hard copy accounts payable subsidiary ledger. Finally, the clerk files the purchase order and invoice in the open accounts payable file in the department. At the end of the day, the clerk prepares a hardcopy journal voucher and sends it to the general ledger department. REQUIRED: Based on the above case, draw: (a) Context diagram (4 Marks) (b) Logical data flow diagram (level 0) (12 Marks)