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

Sales (104 units)		$520,000
Production costs (130 units):
Direct materials	$65,000
Direct labor	16,250
Variable factory overhead	29,250
Fixed factory overhead	26,000	136,500
Operating expenses:
Variable operating expenses	$5,600
Fixed operating expenses	3,640	9,240

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

a.$510,760

b.$426,000

c.$519,870

d.$422,360