On a Linux router, packet forwarding for IPv4 has been enabled. After a reboot, the machine
no longer forwards IP packets from other hosts. The commanD. echo 1 >
/proc/sys/net/ipv4/ip_forward temporarily resolves this issue. Which one of the following
options is the best way to ensure this setting is saved across system restarts?

A.
In /etc/sysctl.conf change net.ipv4.ip_forward to 1.

B.
In /etc/rc.local add net.ipv4.ip_forward = 1.

C.
Add echo 1 > /proc/sys/net/ipv4/ip_forward to any user login script.

D.
Add echo 1 > /proc/sys/net/ipv4/ip_forward to the root user login script.

E.
In /etc/sysconfig/iptables-config add ipv4.ip_foward = 1.