I have already calculated numbers 1 through 4. Please answer question 5!

1. A 10-year bond with 8% annual coupon and 8% yield to maturity. 5.66 years

2.A 30-year bond with 2% annual coupon and 8% yield to maturity. 16.26 years

3. A 100-year bond with 9% annual coupon and 8% yield to maturity 15.17 years

4) A portfolio of bond (1) and (2), with 30.71% invested in bond (1) and 69.29% in bond (2). (Hint: Duration of a portfolio equals the weighted average duration of all bonds in the portfolio) 13.61years

5)An insurance company holds a $100 million asset. The asset stands to lose if interest rate drops. The company estimates the duration of its assets to be 13.49 years and considers one of the above bonds (or portfolio of bonds) in (1)-(4) to hedge the potential loss from the asset. Which one would be the best choice of the insurance company and WHY?