Use this inventory information for the month of July to answer the following question.

July	1		Beginning inventory	10 units @ $120
	5		Purchase	60 units @ $112
	14		Sale	40 units
	21		Purchase	30 units @ $116
	31		Sale	28 units

Assuming that a periodic inventory system is used, what is cost of goods sold under the average-cost method?

a. $3,648

b. $7,888

c. $7,752

d. $3,712