A corporation can cam 7.5% if it invests in municipal bonds. The corporation can also earn 8.40% (before-tax) by investing in preferred stock. Assume that the two investments have equal risk. What is the break-even corporate tax rate that makes the corporation indifferent between the two investments? Assume a 70% dividend exclusion for tax on dividends. (Do not round your intermediate answer and round your final answer to two decimal places.) a. 35.71% b. 32.50% c. 27.50% d. 43.93% O e. 28.57%