At reporting date Guzzle Limited estimated an impairment loss of $50 000 against its single cash-generating unit. The company had the following assets: headquarters building $200 000; plant $120 000; equipment $80 000, goodwill $20 000. The net carrying amount of the headquarters building after allocation of the impairment loss is:

a. $150 000

b. $170 000

c. $175 000

d. $185 000

e. None of the above