Which of the following protocol/authentication standards she must check in email header to analyze the email authenticity?

Racheal is an incident handler working at an organization called Inception Tech. Recently, numerous employees have been complaining about receiving emails from unknown senders. In order to prevent employees from spoof ng emails and keeping security in mind, Racheal was asked to take appropriate actions in this matter. As a part of her assignment, she needs to analyze the email headers to check the authenticity of received emails.

Which of the following protocol/authentication standards she must check in email header to analyze the email authenticity?
A . POP
B . SNMP
C . DKIM
D . ARP

Answer: C