Which of the following statements appropriately describes attributes of perpetual and periodic inventory systems? O a. Historically, a perpetual inventory system is less costly to maintain then a periodic one. O b. Inventory shrinkage is just as easily determined under both the perpetual and periodic inventory system. Oc. The perpetual inventory system computes cost of sales as a residual amount. Od. If a company has a December 31 year end, and operated under the periodic inventory system, it is possible that the balance in the inventory account on December 29 would remain unchanged from its January 1 balance, even though numerous sales have occurred during the year. O e. Cost of sales can be determined at any time by both the perpetual and periodic inventory system without the need of a physical inventory count. Mark