A small consulting firm had the following transactions over a two-month period, December 2016 and January 2017, and no other transactions. Client services were performed and billed during December 2016 for total fees of $57,000. Of this amount, $46,000 was collected in December 2016 and the balance was collected in January 2017. Expenses incurred to service these clients during December 2016 were $40,000, of which $30,000 was paid in December 2016 and the remaining $10,000 was paid in January 2017. Using a cash-based approach, what was the net income for the month of December 2016?

a. $27,000

. b. $6,000.

c. $16,000.

d. $18,000.