HarrisCo uses a periodic inventory system. The company started the month with 6 masks in its beginning inventory that cost $7 each. During the month, HarrisCo purchased 55 additional masks for $9 each. At the end of the month, Harriso counted its inventory and found that 3 masks remained unsold. Using the LIFO method, its cost of goods sold for the month is: Multiple Choice $522. $510. O O O $516 O $21