According to Microsoft’s Security, Compliance, and Identity (SCI) documentation and learning paths (specifically SC-900, SC-300, and Azure AD Identity Protection modules):

“Conditional Access policies in Azure AD are the primary method for enforcing access controls based on specific conditions such as user, group, location, device compliance, and application.”

In this case, the organization can configure a Conditional Access policy that targets a specific Azure AD group and requires MFA as a condition before access is granted. The typical policy setup includes:

Assignments: Target users or groups (e.g., “Finance Department Users”).

Cloud apps or actions: Specify which applications or services are protected (e.g., Microsoft 365).

Access controls: Set the control to “Require multi-factor authentication.”

Microsoft’s SCI training materials further state:

“Conditional Access enables administrators to enforce MFA for specific users, groups, or scenarios. It provides flexibility to protect access without enabling MFA globally for all users.”

Other options explained:

Azure Policy (A) applies to Azure resources, not user authentication.

Communication compliance policy (B) monitors message content for compliance violations.

User risk policy (D) is part of Azure AD Identity Protection, enforcing MFA based on detected user risk levels, not group membership.

Therefore, the verified and correct answer is: ✅ C. a Conditional Access policy.