Peter has just been hired as a network engineer and has recently been examining the company$$s core router configuration. He notices that the current configuration would allow an incoming packet from the Internet to have a source IP address within the $10\mathrm{.}0\mathrm{.}0\mathrm{.}0/8,172\mathrm{.}16\mathrm{.}0\mathrm{.}0/12,$ or $192\mathrm{.}168\mathrm{.}0\mathrm{.}0/16$ address space. Which of the following should Peter do$?$

a$.$ Replace the router with a stateless firewall.

b$.$ Create a rule on the switches that connect to the router to discard any traffic with those addresses in the source IP field.

c$.$ Nothing. The router configuration is correct.

d$.$ Modify the ACL on the router to prevent the traffic from transferring to the internal network from the Internet for those addresses.