A business operated at 100% of capacity during its first month, with the following results:

Sales (120 units)		$600,000
Production costs (150 units):
Direct materials	$75,000
Direct labor	18,750
Variable factory overhead	33,750
Fixed factory overhead	30,000	157,500
Operating expenses:
Variable operating expenses	$6,450
Fixed operating expenses	4,230	10,680

The amount of contribution margin that would be reported on the variable costing income statement is

a.$599,850

b.$589,320

c.$491,550

d.$487,320