Another technician has scribbled some notes about IPv$4$ addresses used in various

networks associated with support tickets. One of them is assigned to the WAN interface

of a SOHO router that requires troubleshooting. Which of these addresses must it be$?$

a$.52\mathrm{.}165\mathrm{.}16\mathrm{.}254$

b$.192\mathrm{.}168\mathrm{.}100\mathrm{.}52$

c$.169\mathrm{.}254\mathrm{.}1\mathrm{.}121$

d$.172\mathrm{.}30\mathrm{.}100\mathrm{.}32$