What best describes two-factor authentication?

A.
Something you know

B.
Something you have

C.
Something you are

D.
A combination of two listed above

Explanation:
D: There are three fundamental types of authentication: authentication by knowledgesomething a person knows, authentication by possessionsomething a person has, and authentication by characteristicsomething a person is. Technical controls related to these types are called factors. Something you know can be a password or PIN, something you have can be a token fob or smart card, and something you are is usually some form of biometrics. Single-factor authentication is the employment of one of these factors, two-factor authentication is using two of the three factors, and three-factor authentication is the combination of all three factors. The general term for the use of more than one factor during authentication is multifactor authentication. Page 59.