You work as an Exchange Administrator for TechWorldInc. The company has a Windows 2008 Active Directory-based network. The network contains an Exchange Server 2010 organization. You are in the process of choosing an authentication method for Exchange ActiveSync. You need an authentication method that requires both, a password and an external device.
Which of the following authentication methods will you choose for Exchange ActiveSync?

A.
Device-based authentication

B.
Basic authentication

C.
Certificate-based authentication

D.
Token-based authentication