The December 31, 2018 Balance Sheet for CalcTex shows that it has $450,000 in total assets and $150,000 in liabilities. In 2019, CalcTex bought new fixed assets valued at $100,000 and liabilities were reduced by $50,000. The accumulated depreciation expense increased by $50,000. Assuming no other transactions occurred in 2019, the retained earnings at the end of 2019 must be: (a) $50,000 (b) $100,000 (c) $Nil (d) $200,000 (e) None of the above