The records of Family Manufacturing show the following information: Estimated manufacturing overhead Estimated machine hours Actual machine hours worked Actual costs incurred: Indirect materials Indirect labor Utilities Insurance Rent $690,000 46,000 60.000 $170,000 230,000 110,000 100,000 80,000 Assuming that overhead is applied based on an overhead rate calculated using machine hours as the base in the highly automated production environment, the amount of over- or underapplied overhead is Oa. $210,000 underapplied. Ob. $50,000 underapplied. Oc. $50,000 overapplied. Od. $210,000 overapplied