XYZ Inc. sells a single product for $10 per unit. Variable production costs are $5 per unit. Fixed overhead costs amount $10,000 per month. Variable selling costs are $1 per unit. Fixed selling costs are $5,000 per month. Last month, the company produced 10,000 units and sold 7,000 units. What was ABC's net operating income? O a. $22,000 O b. $9,000 O c. $13,000 O d. $27,000