The total prime cost of a product was OMR4,200. The variable manufacturing overhead is calculated based on the number of direct labor hours. The variable manufacturing overhead cost per hour is twice the direct labor cost per hour. The fixed manufacturing overhead was OMR3,000. Assuming that direct labor hours were 450 and that the direct labor cost was 40% of direct materials cost, how much is the total manufacturing cost? Select one: O a. OMR15,600 O b. OMR6,600 O c. OMR9,600 O d. OMR7,200 O e. OMR12,600