The information below relates to Derby Manufacturing Company's operations for a recent month. (Assume that all raw materials are direct materials.): Purchases of raw materials........................ $91,000 Direct labor cost........................................ $122,000 Selling costs (total).................................... $42,000 Administrative costs (total)....................... $56,000 Manufacturing overhead costs (total)....... $340,000 Raw materials inventory, beginning.......... $22,000 Work in process inventory, beginning....... $27,000 Finished goods inventory, beginning........ $42,000 Raw materials inventory, ending............... $7,000 Work in process inventory, ending............ $35,000 Finished goods inventory, ending............. $15,000 What was Derby's cost of goods manufactured for the month? a. $545,000 b. $560,000 c. $568,000 d. $587,000