You have a Microsoft Sentinel workspace.

In Microsoft Sentinel, when you identify an alert as a false positive for a specific account, the most efficient way to suppress future alerts for that entity—without affecting others—is to use an automation rule.

Microsoft Sentinel documentation explains:

“Automation rules can automatically close incidents or suppress alerts based on conditions such as user, IP, or entity name. This helps reduce noise and prevent false positives without modifying analytics rules or affecting other entities.”

By configuring an automation rule to auto-close or suppress alerts where the username equals the known account, Sentinel will prevent new alerts for that account while continuing normal detection for others.

Other options are incorrect:

Watchlist (B) only stores reference data; it doesn’t suppress alerts.

Modify analytics rule (C) affects all users, not just one account.

Activity templates (D) are used for entity behavior analysis, not alert suppression.

✅ Correct answer: A. Create an automation rule