Today is 15 November 2021, Sandy just purchased a Treasury bond with a coupon rate of j2 = 3.105% p.a. and a face value of $100 that matures at par. The maturity date of this bond is 15 May 2023. b) Calculate the modified duration of this Treasury bond. Assume the yield rate is j2 = 3.25% p.a. Give your answer in terms of years, rounded to four decimal places. O a. 2.9071 O b. 2.8602 O c. 1.4535 O d. 1.4772