On March 31, 2020, United Corporation acquired for $750,000 cash all the outstanding common stock of National Company when Nationals balance sheet showed net assets of $500,000. Out-of-pocket costs of the business combination may be disregarded. The current fair values of assets and liabilities of National were equal to their carrying amounts except for machine which was less than carrying amount by $ 20,000.The amount of goodwill is:

a.

$ 250,000.

b.

$ 230,000.

c.

$ 200,000.

d.

$ 270,000.