One of the most common defenses for preventing a security breach is a firewall. What is a firewall?

Question $3$ options:

A firewall is a type of worm that generates so much traffic that it can bring entire networks down.

A firewall is an information technology that examines each message that wants entrance to the network, and unless the message has the correct marking, the firewall prevents it from entering the network. Firewalls can be either hardware or software.

A firewall is a network intrusion attack that takes advantage of programming errors or design flaws to grant the attacker elevated access to the network and its associated data and applications

A firewall is an information technology that protects information transmitted with encryption.