What should you do?

Domain.com has employed you as a network administrator. The Domain.com network consists of a single Active Directory domain named Domain.com. All servers on the Domain.com network run Windows Server 2008. Half the client computers run Windows XP Professional, and the rest run Windows Vista. You receive an instruction from the CIO to have certificates implemented for all internal users. To accomplish this you need to determine the appropriate root certificate authority that will accomplish this.
What should you do?

A.
You should consider implementing a Web CA.

B.
You should consider implementing a Subordinate CA.

C.
You should consider implementing a Stand Alone CA.

D.
You should consider implementing an Enterprise CA.

Explanation:
The Enterprise Root CAs along with the Stand Alone Root CAs is the two CA types. Enterprise Root CAs (automatically integrated with Active Directory) is the uppermost trusted CAs of the hierarchy. They possess the certificates which are issued to the users within your organization.
The Stand Alone Root CAs possesses the CAs which you issue to Internet users.