Which of the following statements is TRUE? Select one: a. All of the statements are true. b. A decrease in the interest rate leads to a decrease in the interest income and an increase in the interest expense. c. Convexity results in changes in duration at different yields of a bond d. When interest rate rises sharply, because of convexity, the losses of a bond portfolio estimated using duration tends to lower than the actual losses e. When the leverage adjusted duration gap is equal to zero, the equity of a bank increases when interest rate falls