In $2021,$ interest rates were about $4\mathrm{.}5\%$ and inflation was about $2\mathrm{.}8\%.$ What was the real interest rate in $2021?.$

A$.1\mathrm{.}65\%$

B$.1\mathrm{.}58\%$

C$.1\mathrm{.}61\%$

D$.1\mathrm{.}62\%$