The correct answer is: A. bincard and stores ledger.
A perpetual inventory system is a system of inventory management in which the inventory levels are constantly updated as goods are received and sold. This is in contrast to a periodic inventory system, in which the inventory levels are only updated at regular intervals.
A perpetual inventory system requires the use of a bincard and a stores ledger. A bincard is a card that is kept for each bin or location in the warehouse. The bincard contains information such as the quantity of goods on hand, the reorder point, and the lead time. The stores ledger is a ledger that contains information about all of the goods in the warehouse. The stores ledger includes information such as the quantity on hand, the cost per unit, and the total value of the goods.
The other options are incorrect because they are not used in a perpetual inventory system. A bill of material is a document that lists the materials and components that are required to produce a product. A material requisition is a document that authorizes the purchase of materials. A purchase requisition is a document that requests the purchase of goods or services. An inward invoice is a document that is received from a supplier when goods are delivered. An outward invoice is a document that is sent to a customer when goods are shipped.