Which of the following is one of the four bases for authentication credentials?

• A. What you know
• B. What you have
• C. Both A and B
• D. Neither A nor B

Answer: (C)

Authentication uses multiple factors, grouped into four bases: something you know, something you have, something you are, and something you do. The question asks for one of these bases, and both “what you know” and “what you have” are valid bases on their own. The best choice acknowledges that both are bases, which is why it’s correct to say that the combination of both factors reflects the concept. In practice, using either a password (what you know) or a hardware token (what you have) for authentication is common, and combining them (two-factor authentication) strengthens security.