You have an Office 365 tenant that has an Enterprise E3 subscription. You configure multi-factor authentication for all users in the tenant. Remote users configure Outlook 2016 to use their Office 365 credentials.
You need to ensure that users only authenticate with Office 365 by using two-step verification.
What should you do?

A.
Disable app passwords for the user accounts.

B.
Remove the rights management license from the user accounts.

C.
Modify the license type of the user accounts to an Enterprise E1 subscription.

D.
Add the user accounts to a new security group.

Explanation:

All the Office 2016 client applications support multi-factor authentication through the use of the Active Directory
Authentication Library (ADAL). This means that app passwords are not required for Office 2016 clients.
References:https://support.office.com/en-us/article/Set-up-multi-factor-authentication-for-Office-365-users-
8f0454b2-f51a-4d9c-bcde-2c48e41621c6