Which are used for security purposes?
(A) Password.
(B) Firewall.
(C) Authentication.
(D) Encryption.

Hint: We all know that network security mixes multiple layers of defenses at edge and in a given network. Every network security’s layer implements policies also as management. Licensed users gain access to network resources, however malicious acts are a unit block from winding up exploited together with threats.

Complete step by step solution:
Firewall area unit used for security purpose;
A firewall may be a network security system designed to stop unauthorized access to or from a personal network. Network firewalls area unit of times accustomed to stop unauthorized net users from accessing personal networks connected to the net, particularly intranets. Firewall has two network interfaces: one for the external facet of the network, one for the inner facet. Its purpose is to regulate what traffic is allowed to traverse from one facet to the opposite because at the most simple level, firewalls will block traffic supposed for specific science addresses or server ports. Digitization has reworked our world. However we tend to live, work, play, and learn have all modified. Each organization that desires to deliver the services that customers and staff demand should defend its network. Network security additionally helps you defend proprietary info from attack. Ultimately it protects your name.
Therefore correct answer is possibility B i.e. Firewall is employed for security purposes.

Note:
Note that firewalls scan packets for malicious code or attack vectors that have already been known as established threats. If a knowledge packet is flagged and determined to be a security risk, the firewall prevents it from coming into the network or reaching your computer.