Option A is the best answer because the .xlsm extension specifically indicates a macro-enabled Excel document . In malware forensics, the most direct indicator of risk in such a file is the presence of macro- containing streams or embedded VBA content . When investigators suspect a malicious Office document, they first determine whether executable macro content exists, because that is often the primary mechanism used to deliver or launch malicious behavior.
While external links, metadata, and unusual size can all be useful supporting indicators, they are not as central to the threat profile of an XLSM file as macro content is. The extension itself points the examiner toward macro analysis as the most relevant first focus. If macros are present, they can be reviewed for suspicious functions, obfuscation, PowerShell or shell commands, downloader behavior, and other signs of malicious intent.
Therefore, from a CHFI-style malware-document analysis perspective, the investigator should first focus on whether the file contains macro-related streams , because that is the clearest and most direct source of malicious functionality in a macro-enabled Excel document.