The management of Harper Corporation, a manufacturing company, has provided the following financial data for December. The contribution margin for December was: Sales Variable production expense.......... Fixed production expense $480,000 $76,000 $85,000 Variable selling expense $18,000 Fixed selling expense. $83,000 Variable administrative expense.... $46,000 Fixed administrative expense...... $108.000 Select one: O a. $319,000 O b. $204,000 c. $340,000 d. $64,000