The annual holding cost as a percentage is 15%, cost per order is $50 and annual demand is 9000 units. The supplier offers the following quantity discount: 1-999 units, the unit cost is $10, 1000-1499, the units cost is $9.9, 1500-1999 units, the unit cost is $9.8, 2000 units and more, the unit cost is $9.7. The total cost at the best quantity is:

Select one:

a. $90000

b. $87300

c. None of the above

d. $88980

e. $91293