what is the function of the protect-loopback filter?

[edit interfaces]
user@router# show
…
lo0 {
unit 0 {
family inet {
filter {
input protect-loopback;
}
address 192.168.100.1/32;
}}}

Given the configuration shown in the exhibit, what is the function of the protect-loopback
filter?

A.
to protect the Routing Engine

B.
to protect all interfaces on the device

C.
to protect the Packet Forwarding Engine

D.
to protect the management interface