Bob is a Junior Administrator at ABC.com is searching the port number of POP3 in a file.
The partial output of the file is look like:

In which file he is searching?

A.
services

B.
protocols

C.
hosts

D.
resolve.conf

Explanation:
The port numbers on which certain standard services are offered are defined in the RFC 1700 Assigned Numbers. The /etc/services file enables server and client programs to convert service names to these numbers -ports. The list is kept on each host and it is stored in the file /etc/services.