Firewall is the correct answer for the above question.
Explanation:
A firewall is used to block unwanted sites for any users of the network. It can be software or hardware or both. It is also called a system because it can be a mixture of the software and the hardware.
It is used to block unwanted sites. When any user does not want to access any sites from the computer system, then he blocks the sites with the help of this.
The above question asked about the system which is used to block unwanted information. This system is known as a firewall. Hence the answer is FIrewall.
