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 unit cost is $9.9, 1500-1999 units, the unit cost is $9.8, 2000 units and more, the unit cost is $9.7. The economic quantity discount when the unit cost is $9.9 is approximate:

Select one:

a. 779

b. 787

c. 1090

d. 990

e. 979