The correct answer is D. In a brokerage environment, emails from an unknown sender with an attachment should be treated as a potential cyber security threat because opening the attachment could expose client personal information, brokerage systems, or internal records to malware, phishing, or unauthorized access. The safest first step is to avoid opening the email or attachment and report it to the IT department or designated internal security contact for proper review.

This aligns with sound information management and privacy protection practices. Brokerages are expected to protect confidential client information and maintain secure handling of records. Internal reporting allows the organization to investigate the message safely, identify whether it is malicious, warn other staff if needed, and preserve evidence for security response. Forwarding the email to a colleague, as in A, increases the risk of spreading the threat. B may remove the immediate message, but it bypasses proper internal reporting and may prevent the organization from identifying a broader attack. C is better than opening it, but simply moving it to junk still fails to escalate the threat appropriately.

From a RIBO-related professionalism and confidentiality perspective, protecting client information means using the brokerage’s approved security process first: do not open it, and report it immediately.