What Was the Amount of Direct Materials Used During November

What was the amount of direct materials used during November if $20,000 in raw materials were purchased during the month,all raw materials are direct,and if the inventories were as follows?
$\begin{array}{|l|r|r|}\hline & \text { Balance November 1 } & \text { Balance November 30 } \\\hline \text { Raw materials } & \$ 4,000 & \$ 3,000 \\\hline \text { Work in process } & \$ 12,000 & \$ 15,000 \\\hline \text { Finished goods } & \$ 24,000 & \$ 27,000 \\\hline\end{array}$

A) $15,000.
B) $20,000.
C) $21,000.
D) $24,000.