authentication question

[CISSP_Candidate]

How can an individual best be authenticated?
A)User id and password
B)Smart card and pin code
C)Two Factor authentication
D)Biometrics

I found this on the quiz and the answer given was D, I thought and still think two factor is the right answer. The commenter suggests that unless 2 factor includes Biometrics then it wouldn't best authenticate.
Wouldn't the question have read, How can an individual best be identified, for Biometrcs to hold good?

[Jescoi]

Yes, and D is right.

Why?

a,b and c are all two factor authentications. It deals with what you are, what you know, what you have, to make you confusion.
The keyword here is individual.

And biometrics deals with individual.