Spencer Inc. applies overhead to production at a predetermined rate of 80% based on direct labor cost. Job No. 130, the only job still in process at the end of August, has been charged with manufacturing overhead of $6,400. What was the amount of direct materials charged to Job 130 assuming the balance in Work in Process inventory is $20,000? A) $20,000 B) $5,600 C) $7,000 D) $6,400