Thanos uses the specific identification formula of costing inventory. During March, Thanos purchased three infinity stones: a Space Stone for $4,800, a Mind Stone for $6,400, and a Power Stone $8,400, respectively. During March, two stones are sold to Thor for $8,600 each. Thanos determines that at March 31, the Power Stone is still on hand. What is Thanos's cost of goods sold for March? $11,200 $17,200 O $15,700 $13,500