Which of these addresses would be considered a private address $($RFC $1918$ address$)?$

A$.172\mathrm{.}128\mathrm{.}10\mathrm{.}5$

B$.9\mathrm{.}10\mathrm{.}10\mathrm{.}7$

C$.172\mathrm{.}20\mathrm{.}128\mathrm{.}240$

D$.250\mathrm{.}28\mathrm{.}17\mathrm{.}10$