Two-Factor Authentication

A.

Two-factor authentication (2FA) is a security method that requires two different forms of identification in order to access a system or resource. The goal of 2FA is to increase security by making it more difficult for unauthorized individuals to gain access, even if they have stolen or guessed a user's password.

Out of the options provided, only one is a true example of two-factor authentication, which is option C: Fingerprint and iris scan. This is because it requires two separate forms of biometric identification - a fingerprint scan and an iris scan - in order to authenticate a user's identity.

Option A, bank card and PIN, is not an example of two-factor authentication because both the card and the PIN are something that the user possesses. While a bank card may be physically separate from the PIN, it is still considered a single form of identification.

Option B, username and password, is also not an example of two-factor authentication because both pieces of information are something that the user knows. Even if the username is considered public information, the combination of the username and password is still only one form of identification.

Option D, key and proximity badge, is also not an example of two-factor authentication. While the two items are physically separate, they are still both something that the user possesses.

In conclusion, the correct answer is option C: Fingerprint and iris scan, which is an example of two-factor authentication that requires two different forms of biometric identification to authenticate a user's identity.