How Microsoft 365 defends employee accounts and organizational data against cyber attacks is the correct concern.

This is a primary issue because moving to a SaaS productivity suite shifts responsibility for many security controls to the vendor and because compromised user accounts and email are a common way attackers gain access to corporate data.

You should evaluate identity protection such as Azure Active Directory features like multi factor authentication and conditional access, threat protection such as Microsoft Defender for Office 365, and information protection such as Data Loss Prevention and sensitivity labels to understand the platform defensive posture and incident response capabilities.

How well Microsoft 365 integrates with Google Cloud Identity for unified access control is not the best answer because cross identity integration is a specific operational consideration and can often be solved with federation and provisioning tools, but it is narrower than the overarching risk of account compromise and data breaches.

Whether the Microsoft 365 user experience will require extensive retraining for staff is more of an adoption and change management concern rather than a core security risk, so it is not the primary focus for a chief information security officer planning migrations.

The pricing differences between Microsoft 365 subscription tiers are an important procurement topic but they are not the central security concern when assessing how to protect accounts and data during and after migration.

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