The netstat output shows that multiple ports are open, including Telnet (23), FTP (20), and TFTP (69), which are potential security risks. Disabling unused ports minimizes the attack surface, reducing security vulnerabilities.

Breakdown of Options:

A. Disable the unused ports – Correct answer. Unused ports should be closed to prevent unauthorized access.

B. Enforce access control lists – ACLs help control access but do not disable unnecessary services.

C. Perform content filtering – Content filtering controls web traffic, not port security.

D. Set up a screened subnet – A DMZ (screened subnet) improves security but does not address open ports.