Which port does the Post Office Protocol Version 3 (POP3) make use of?

A.
110

B.
109

C.
139

D.
119

Explanation:
POP3 uses port 110.
Incorrect Answers:
B: Port 109 is used by POP2.
C: Port 139 is used by the NetBIOS Session Service.
D: Port 119 is used by NNTP.

https://en.wikipedia.org/wiki/List_of_TCP_and_UDP_port_numbers