Which of the following best distinguishes between an Anti$-$Virus and a Firewall?

"Firewalls only block external threats, anti$-$virus only blocks internal threats"

"Firewalls attempt to block threats from incoming data, anti$-$virus attempts to block malicious software already on the computer"

Firewalls are hardware devices; anti$-$virus are software

"Firewalls scan files, anti$-$virus monitors and filters a network"