To protect the computer system against the hacker and different kind of viruses, one must always keep _________ on in the computer system.

A) Script

B) Antivirus

C) VLC player

D) Firewall

Correct Answer : Firewall

Explanation : It is essential to always keep the firewall on in our computer system. It saves the computer system against hackers, viruses, and installing software form unknown sources. We can also consider it the first line of defense of the computer system.