At the End of 2016,a Company Reported Cost of Goods

At the end of 2016,a company reported cost of goods sold of $4,800,which represented 80% of the goods available for sale.The beginning inventory amount was twice as much as the ending inventory amount.What was the amount of purchases for 2016?

A) $1,200
B) $2,400
C) $3,600
D) $5,400