Which of the following statements is correct, other things held constant? a. interest rates on all debt securities tend to rise during recessions because recessions increase the possibility of bankruptcy, hence the riskiness of all debt securities. b. if companies have fewer good investment opportunities, interest rates are likely to increase. c. if individuals increase their savings rate, interest rates are likely to increase. d. if expected inflation increases, interest rates are likely to increase. e. interest rates on long-term bonds are more volatile than rates on short-term debt securities like t-bills.