$3.$ Grace Lang thinks that the recent Federal Reserve policy is going to push the interest rates down. She is considering keeping only one of the three bonds in her portfolio. She knows that bond A has a duration of $3\mathrm{.}734,$ bond B has a duration of $3\mathrm{.}567,$ and bond C has the following characteristics:

Par Value $1,000$

Life $4$ years

Coupon Rate $6\%$

Discount rate $10$percent

Which one of the three bonds should she keep? Why? Explain.