A business operated at 100% of capacity during its first month and incurred the following costs:

Production costs (20,000 units):Direct materials$180,000Direct labor240,000Variable factory overhead280,000Fixed factory overhead100,000$800,000Operating expenses:Variable operating expenses$130,000Fixed operating expenses50,000180,000

If 1,600 units remain unsold at the end of the month, what is the amount of inventory that would be reported on the variable costing balance sheet?

a.$66,400

b.$56,000

c.$64,000

d.$78,400