Mark Achin sells 3,600 electric motors each year. The cost of each electric motor is $200, and demand is constant throughout the year. The cost of placing an order is $40, while the holding cost is 10% of unit cost per year. There are 360 working days per year and the lead-time is 5 days. What is his economic order quantity in units?

A) 100

B) 200

C) 60

D) 120