If the risk$-$free rate of interest $(r_f)$ is $10\%,$ then you should be indifferent between receiving $$100$ in one year or

A$.$ $$109\mathrm{.}09$ today.

B$.$ $$90\mathrm{.}91$ today.

C$.$ $$100\mathrm{.}00$ today.

D$.$ none of the above