The correct answer is D.
OBJ-2.3: Based on the open ports, it is likely that the host is a networked printer. Port 515 is used as an LPR/LPD port for most printers and older print servers. Port 631 is used for IPP for most modern printers and CUPS-based print servers. Port 9100 is used as a RAW port for most printers and is also known as the direct-IP port. If any of these three ports are found, the host is likely a printer. If ports 135, 139, 445 are found, this is usually a good indication of a Windows file server. Port such as FTP, telnet, SMTP, and http is used by both Windows and Linux servers; therefore, they are not as helpful to indicate which operating system is in use by the host.