Which of the following is an example of a "something you are" authentication factor?

The choice that represents a "something you are" authentication factor is indeed a photograph of your face. This type of authentication relies on biometric data, which is unique to an individual. Biometrics encompasses various physical characteristics such as fingerprints, facial recognition, iris patterns, and voice, all of which are inherent to a person and cannot be easily replicated or transferred.

In the context of authentication, "something you are" factors are used to verify an individual's identity based on biological traits, making them generally more secure than traditional forms of authentication, such as passwords or PINs. The use of facial recognition exemplifies this principle, as it leverages the unique features of one’s face for identity verification.

In contrast, the other options represent different categories of authentication factors. A credit card is an item that you have, passwords and PINs are forms of knowledge (something you know), and a user ID is also categorized under something you know. Each of these alternatives does not provide the same level of uniqueness and difficulty to replicate as biometric data does, highlighting the distinctiveness and reliability of "something you are" as an authentication method.