ControlBond Maturity Coupon Yield to Maturity

A $515\%12\%$

B $128\%10\%$

C $205\%3\%$

D $157\%7\%$

Consider the bonds above. If you expect the yield curve to flatten over the next $1-2$ years, which two bonds might you buy to create a portfolio that is will perform the best against any other pair if your duration target is in the medium term $(7-13$ years$)?$