$28.$ If a fixed$-$income portfolio manager expected interest rates to increase in the near future and wanted to use Treasury bond futures to reduce the portfolio's duration. Which of the following actions should the portfolio manager take to accomplish this?

A$.$Short Treasury bond futures.

B$.$Buy $($go long$)$ Treasury bond futures,

C$.$Treasure bond futures positions will not affect a portfolio's duration.

I know Short Treasury bond future is correct answer, but i want to know why it it the right answer $?$ please let me know the logic behind it$.$ Thank you

$29.$ An analyst is examining the risk and return characteristics for a $3-$year, $2\%$ bond that is callable at par after one year, and a $2-$year, $1\mathrm{.}5\%$bond that is putable after one year. Both of the bonds are trading at par.

Which of the two bonds is most likely to exhibit negative convexity, the callable or the putable bond?

For a given decrease in interest rates, which of the two bonds is more likely to exhibit lower upside potential?

A$.$The callable bond; the callable bond.

B$.$The callable bond; the putable bond.

C$.$ The putable bond; the callable bond.

please let me know the logic behind it$.$