Crag Co has sales of $200m per year and the gross profit margin is 40%. Finished goods inventory days vary throughout the year within the following range:
All purchases and sales are made on a cash basis and no inventory of raw materials or work in progress is carried. Crag Co intends to finance permanent current assets with equity and fluctuating current assets with its overdraft.
In relation to finished goods inventory and assuming a 360-day year, how much finance will be needed from the overdraft？

A. $10m
B. $17m
C. $30m
D. $40m