Within Microsoft Purview, Insider Risk Management is the solution that is explicitly designed to detect activities such as IP theft and data leakage. Microsoft describes it as a compliance solution that correlates many user and system signals to identify potentially malicious or inadvertent insider risks, including leaks of sensitive data and data spillage.

Organizations create Insider Risk Management policies that watch for risky behaviors such as unusual file downloads, copying data to removable media, or sharing sensitive information to external locations. When configured with templates like Data leaks, these policies can use high-severity alerts from Data Loss Prevention (DLP) policies as triggers, so that suspected data-leak events automatically generate alerts and cases for investigation. This workflow lets investigators quickly triage, investigate, and remediate possible data-exfiltration incidents.

The other options serve different purposes. Compliance Manager evaluates and tracks compliance posture against regulations and internal controls, rather than monitoring user behavior for leaks. Communication compliance focuses on inappropriate or non-compliant messages (such as harassment or improper sharing in chats and email). eDiscovery is used to find and preserve existing content for legal or investigative cases, not for proactive detection of leakage as it occurs.

Therefore, the Microsoft Purview solution used to identify data leakage is Insider Risk Management.