Final answer:
Moving publicly accessible systems to a secured demilitarized zone (DMZ) is a Network Security Measure designed to provide an additional layer of defense against external threats while allowing services to outside users. the correct option is a. Network Security Measures .
Step-by-step explanation:
Moving all publicly accessible systems and services to a secured demilitarized zone (DMZ) is an example of a. Network Security Measures. The DMZ acts as a separate network segment that provides an additional layer of security between the public internet and an organization's internal network. This is done to prevent unauthorized access to internal systems and data while still providing services to external users.
By placing servers, such as web servers or FTP servers, within the DMZ, organizations can ensure that if these systems are compromised, the attacker still does not have direct access to the sensitive data stored on the internal network. Firewall and other monitoring tools are typically used to control and inspect the traffic coming into and going out of the DMZ, further enhancing security.