A. A physical barrier used to prevent unauthorized access to a computer network
B. A software program or hardware device that monitors and controls incoming and outgoing network traffic
C. A type of malware
D. A social media platform

Solution

B. A software program or hardware device that monitors and controls incoming and outgoing network traffic

Explanation

A firewall is a cybersecurity measure used to monitor and control incoming and outgoing network traffic based on predetermined security rules, protecting against unauthorized access and cyberattacks.