Which subnet is used to address an internal$-$only network while conforming to RFC $1918?100\mathrm{.}0\mathrm{.}0\mathrm{.}0/10$

$169\mathrm{.}254\mathrm{.}0\mathrm{.}0/16$

$172\mathrm{.}20\mathrm{.}0\mathrm{.}0/16$

$192\mathrm{.}168\mathrm{.}0\mathrm{.}0/15$