What Is Done with Factory Overhead in Normal Costing

What is done with factory overhead in normal costing?

A) The balance in factory overhead at the end of the accounting period is closed.
B) Different overhead rates are used for different quantities of predicted activity.
C) The balance in factory overhead at the end of the accounting period is kept open.
D) The immaterial balance in factory overhead at the end of the accounting period is allocated to the cost of goods sold and inventory accounts.