Refer to the Following Data ? Using the Gross Profit Method of Inventory Estimation, the month

Refer to the following data: $\begin{array}{lr}\text { Net sales, first month } & \$ 13,000 \\\text { Normal gross profit as a percentage of sales } & 45 \% \\\text { Inventory, start of period } & \$ 8,000 \\\text { Net purchases, first month } & \$ 7,000\end{array}$ ? Using the gross profit method of inventory estimation, the cost of goods sold would be

A) $5,850.
B) $7,150
C) $7,850
D) $15,000.