The Balances in Dellco Company's Accounts at the End of the Period

The balances in Dellco Company's accounts at the end of the period were: $\begin{array}{lr}\text { Work in Process Inventory } & \$ 40,000 \\\text { Finished Goods Inventory } & 60,000 \\\text { Cost of Goods Sold } & 300,000 \\\text { Manufacturing Overhead (credit balance) } & 12,000\end{array}$ If the balance in the Manufacturing Overhead account is considered immaterial, which of the following represents the amounts that should be adjusted to the Work in Process Inventory account?

A) $0
B) Debit of $12,000
C) Credit of $12,000
D) Credit of $9,000