The correct answer is D.
OBJ-1.5: Port 25 is the default port for SMTP (Simple Message Transfer Protocol), which is used for sending an email. An active mail relay occurs when an SMTP server is configured in such a way that it allows anyone on the Internet to send email through it, not just mail originating from your known and trusted users. Spammers can exploit this type of vulnerability to use your email server for their own benefit. File/print sharing usually operates over ports 135, 139, and 445 on a Windows server. Web portals run on ports 80 and 443. Clear text authentication could occur using an unencrypted service, such as telnet (23), FTP (20/21), or the web (80).