Concept:A firewall is a security system that protects a network by controlling traffic.
Explanation:A firewall can exist as either software or hardware.
It monitors data that enters and leaves a computer system or website.
It compares the traffic against a set of security rules.
Safe or authorised data is allowed through the firewall.
Suspicious data and unauthorised access are blocked.
This action prevents hackers and malicious software from reaching the protected system.
Hardware firewalls usually protect an entire network, while software firewalls often protect a single device.
In every case, the firewall serves as a cyber security tool.
Therefore, the main function of a firewall is to ensure cyber security.
Answer:B. Cyber security