The following data pertain to a recent period's operations:

Sales.......................................................... ?

Beginning finished goods inventory......... $12,000

Cost of goods manufactured..................... $36,000

Ending finished goods inventory.............. $6,000

Cost of goods sold.................................... ?

Gross margin............................................. 40% of Sales Administrative and selling expenses......... $10,000 Net operating income................................ ?

Net operating income was: a. $18,000 b. $10,000 c. $14,000 d. $46,000