The correct answer is: B. Firewall
A firewall is a network security device that monitors and controls incoming and outgoing network traffic based on predetermined security rules. It is a barrier that protects a computer network from unauthorized access by hackers.
A hacker-proof program is a program that is designed to be immune to hacking attacks. However, no program is 100% hacker-proof, as hackers are constantly finding new ways to exploit vulnerabilities.
A hacker-resistant server is a server that is designed to be resistant to hacking attacks. However, no server is 100% hacker-resistant, as hackers are constantly finding new ways to exploit vulnerabilities.
Encryption safe wall is not a technical term. It is not a type of firewall or security device.