To hide the 1 - Critical priority incidents for ITIL users viewing the dashboard, the correct Breakdown Source security configuration would need to use a blacklist security type, as this explicitly prevents certain elements from being displayed. Given the options: C. Security type: Blacklist / All roles: checked / Elements: 2 - High, 3 - Moderate, 4 - Low, 5 - Planning This configuration would effectively hide the '1 - Critical' incidents from ITIL users since it blacklists all other priorities for visibility, implying that '1 - Critical' is not visible to any role.