The total assets of Gunther Inc. increased by $$4,105$ during the year. However, there was no change in its liabilities. Which of the following statements in the current scenario is true?

a$.$ Gunther's total stockholders' equity must have increased by $$4,105.$

b$.$ Gunther's total stockholders' equity must have decreased by $$4,105.$

c$.$ Gunther's cash flow from investing activities must have decreased by $$4,105.$

d$.$ Gunther's cash flow from investing activities must have increased by $$4,105.$