Exam 312-50v8 topic 2 question 5 discussion

A penetration tester is conducting a port scan on a specific host. The tester found several ports opened that were confusing in concluding the Operating System
(OS) version installed. Considering the NMAP result below, which of the following is likely to be installed on the target machine by the OS?
Starting NMAP 5.21 at 2011-03-15 11:06
NMAP scan report for 172.16.40.65
Host is up (1.00s latency).

Not shown: 993 closed ports -

PORT STATE SERVICE -
21/tcp open ftp
23/tcp open telnet
80/tcp open http
139/tcp open netbios-ssn
515/tcp open
631/tcp open ipp
9100/tcp open

MAC Address: 00:00:48:0D:EE:89 -