Last year Vaughn Corp. had sales of $315,000 and a net income of $17,832, and its year-end assets were $210,000. The firm's total-debtto-total-assets ratio was 52.5%. Based on the DuPont equation, what was Vaughn's ROE? Select the correct answer. a. 16.82% b. 18.41% c. 18.94% d. 17.35% e. 17.88%