Office 365 users from changing their display names by using Outlook Web App

You need to prevent Office 365 users from changing their display names by using Outlook Web App. What should you do?

A. Modify the default role assignment policy.
B. Modify the default email address policy.
C. Run the Set-MsolCompanyContactInformation Windows PowerShell cmdlet.
D. Run the Set-MsolUserPrincipalName Windows PowerShell cmdlet.

Correct Answer: A