Please help, it's urgent.

Pioneer Limited purchases a product which has a steady monthly demand of 20 000 units. The product costs R100 per unit. The ordering cost is R5 per order. The holding cost is 10% of the unit purchase price. Which one of the following represents the annual economic order quantity (rounded off to the next whole number)? Select one: O A. 142 O B.980 O C. 283 D. 490