You need the Automated Investigation and Response (AIR) remediation level for Device1 set so that all remediation actions require approval. What should you create to target Device1?

A device group is the correct choice because Automated Investigation and Response (AIR) remediation levels are configured within Microsoft Defender for Endpoint and are applied to devices based on their membership in device groups. By creating a device group specifically for Device1 and configuring its AIR settings to require approval for all remediation actions, you achieve the desired outcome. A security group is used for managing user and computer access to resources, not for configuring Defender for Endpoint remediation levels. An administrative unit is used to delegate administrative permissions over a subset of users or devices in Azure AD, which is not directly related to AIR settings. An action group is used in Azure Monitor to trigger notifications or actions based on alerts, not for defining remediation approval levels in Defender for Endpoint.