Based on the term structure of interest rate, calculate the one$-$year forward rate three years from now if three$-$ and four$-$year spot rates are $5\mathrm{.}50\%$ and $5\mathrm{.}80\%,$ respectively?

A$.3\mathrm{.}62\%$

B$.4\mathrm{.}50\%$

C$.5\mathrm{.}78\%$

D$.6\mathrm{.}71\%$