please answer correct with detailed explanation

On December 31, 2018,M Co acquired 100% ownership of S Co. On that date, S reported assets and liabilities with book values of $300,000 and $100,000, respectively, common stock outstanding of $50,000, and retained earnings of $150,000. The book values and fair values of S assets and liabilities were equal except for land which had increased in value by $10,000 and inventories which had decreased by $10,000 Based on the preceding information, what amount of goodwill balance immediately after the business combination, if the acquisition price was $240,000? Select one: a. 45,000 b. 30,000 c. 40,000 d. 35,000