Suppose that the current one$$year rate and expected one$$year interest rates over the following $3$ years are: $1$R$1=6\%,$ E$(2$r$1)=7\%,$ E$(3$r$1)=7\mathrm{.}5\%$ and E$(4$r$1)=7\mathrm{.}85\%$

According to UET, what is the current rate four$-$year interest rate?

Group of answer choices

$9\mathrm{.}21\%$

$7\mathrm{.}085\%$

$6\mathrm{.}5\%$

$6\mathrm{.}83\%$