Establishing workspace-level isolation with individual workspaces for each team, secured by Azure Active Directory groups, is the most effective approach. This method ensures that each team operates in its own isolated environment, significantly reducing the risk of unauthorized access to sensitive datasets by other teams. While fine-grained access control and data governance tools like Azure Purview are beneficial, they do not offer the same level of isolation. Open access with post-factum auditing is not a proactive security measure and fails to prevent unauthorized access initially.