You have an Exchange organization. All servers in the organization have Exchange Server
2010 Service Pack 1 (SP1) installed.
The network contains an internal root certification authority (CA).
Users on the network use Outlook Anywhere. A Client Access server uses a wildcard
certificate issued by a trusted third-party root CA
You need to ensure that users can send and receive encrypted e-mail messages by using
S/MIME.
What should you do?

A.
Instruct all users to import the internal root CA certificate.

B.
Import the internal root CA certificate to the Client Access server.

C.
Instruct all users to import the third-party root CA certificate.

D.
Issue a certificate to each user from the internal root CA.