A bond is currently trading for 98.72 per 100 of par value. If the bond's yield-to- maturity (YTM) rises by 100 basis points, the bond's full price is expected to fall to 93.66. If the bond's YTM decreases by 100 basis points, the bond's full price is expected to increase to 105.78. The bond's approximate modified duration is closest to:

a) 122.78

b) 12.28

c) 6.14

d) 61.34