The following is a Taylor$-$rule for country D$,$

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$r=0\mathrm{.}02+0\mathrm{.}4(\frac{Y-Y^{**}}{Y^{**}})+0\mathrm{.}5$

where $r$ is the real cash rate $($interest rate, policy rate set by the Central Bank of country $D),Y$ is output, $Y***$ is potential output and $$ is the rate of inflation. According to this Taylor rule, if the output of country $D$ is at its potential level and inflation is $1\%,$ what will be the value of the real cash rate, $r?$

a$.6\mathrm{.}5\%$

b$.0\%$

c$.5\%$

d$.1\%$

e$.2\mathrm{.}5\%$