You need to ensure that the remote users who have a mailbox on EX1 can access their mailbox by using Outlook Anywhere

Your network contains an Active Directory forest named contoso.com. The forest contains one
domain.
You have an Exchange Server organization that contains three servers. The servers are configured as
shown in the following table.

An administrator implements Outlook Anywhere on Exchange Server 2013.
Remote users who have a mailbox hosted on EX1 report that they receive the following error
message when they attempt to configure a Microsoft Outlook profile.

Remote users who have a mailbox hosted on EX3 can configure an Outlook profile successfully.
You need to ensure that the remote users who have a mailbox on EX1 can access their mailbox by
using Outlook Anywhere.
What should you do?

A.
On EX2, run Set-OutlookAnywhere

B.
On EX2, run Set-CasMailbox.

C.
On EX1, run Enable-OutlookAnywhere

D.
On EX1, run Set-OutlookAnywhere