You are conducting a security audit. While reviewing configuration files and logs, you notice logs accepting POP3 traffic, but you do not see a rule allowing POP3 traffic in the Rule Base. Which of the following is the most likely cause?

A.
The POP3 rule is disabled.

B.
POP3 is one of 3 services (POP3, IMAP, and SMTP) accepted by the default mail object in R75.

C.
POP3 is accepted in Global Properties.

D.
The POP3 rule is hidden.