Which one of the following statements is correct? Select one: a. When FIFO is used, cost of goods sold can be different in periodic and perpetual systems ob. When the weighted average method is used, ending inventory is usually the same in periodic and perpetual systems c. When weighted average is used in a periodic system, average cost is recalculated after each purpose if the unit purchase cost changes Od. When the weighted average method is used, ending inventory may be different in periodic and perpetual systems e. When the weighted average method is used, cost of goods sold is usually the same in periodic and perpetual systems