Best Diamond Co. uses a perpetual inventory system and the specific identification cost formula. Below is the company's beginning inventory, purchases and sales transactions for the month of December. Unit Cost Unit Cost Quantity $1,200 Beginning Inventory (Dec 1) Diamond #234 Diamond # 435 Diamond #654 Jan 6 Purchase Diamond # 765 1 2 $1,200 2.400 3,500 4500 1 1 4800 3,500 4500 Jan 4 Sold Diamond # 654 for $4,000 Jan 15 Sold one Diamond # 435 for $3,000 and Diamond # 234 for $2,000 Determine the cost of goods sold for the month of January O $6,000 O $1,200 $4,500 O $7,100