Explanation/Reference:
Explanation:
A: Multi-Factor Authentication comes as part of the following offerings:
Azure Active Directory Premium licenses - Full featured use of Azure Multi-Factor Authentication

Service (Cloud) or Azure Multi-Factor Authentication Server (On-premises).
Multi-Factor Authentication for Office 365

Azure Active Directory Global Administrators

C: MFA Enabled by conditional access policy. It is the most flexible means to enable two-step verification for your users. Enabling using conditional access policy only works for Azure MFA in the cloud and is a premium feature of Azure AD.
References:
https://docs.microsoft.com/en-us/azure/active-directory/authentication/howto-mfa-getstarted Question Set 1