The following lots of a Commodity P were available for sale during the year. Beginning inventory First purchase Second purchase Third purchase 5 units at $61 15 units at $63 10 units at $74 10 units at $77 The firm uses the periodic system, and there are 20 units of the commodity on hand at the end of the year. What is the amount of cost of goods sold for the year according to the average cost method? Oa. $1,375 Ob. $1,380 Oc. $1,250 Od. $1,510