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

Sales (112 units)		$560,000
Production costs (140 units):
Direct materials	$70,000
Direct labor	17,500
Variable factory overhead	31,500
Fixed factory overhead	28,000	147,000
Operating expenses:
Variable operating expenses	$5,290
Fixed operating expenses	3,870	9,160

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

a.$550,840

b.$559,860

c.$455,640

d.$459,510