A member of the human resources department received the following email message after sending an email containing benefit and tax information to a candidate:
"Your message has been quarantined for the following policy violation: external potential_PII. Please contact the IT security administrator for further details".
Which of the following BEST describes why this message was received?
A. The DLP system flagged the message.
B. The mail gateway prevented the message from being sent to personal email addresses.
C. The company firewall blocked the recipient’s IP address.
D. The file integrity check failed for the attached files.