What security technology is the right fit?

Your organization wants to provide virtual private network connectivity from outside the office, but additional security is required. The primary requirement is that each user is verified with a username, password, and a piece of information that physically identifies the user. What would be the most appropriate solution for this requirement?

A) Specially configured BIOS settings on each remote device

B) Installation of anti-virus and anti-spyware software on each remote device

C) Daily Windows event viewer reports

D) A token-generator synchronized with each end user