6. Which of the following statements is/are true? I. Dividends paid on preferred stock are not tax-deductible. II. Unpaid dividends on preferred stock trigger default of the firm because preferred stock is often considered as a fixed-income security. III. If preferred dividends are cumulative, then preferred dividends not paid in a particular year will be carried forward to the next year. A) I only B) I and III only C) II and III only D) All of the above E) None of the above