If Susan’s organization requires her to log in with her username, a PIN, a password, and a retina scan, how many distinct types of factor has she used? One Two Four Three

In the context of authentication, factors are typically categorized into three distinct types: 1. **Something you know**: This includes information that a user knows, such as a username, password, or PIN. 2. **Something you have**: This includes physical items that a user possesses, such as a smart card or a mobile device that might receive a code. 3. **Something you are**: This includes biometric identifiers, such as a fingerprint or retina scan. In Susan's case: - **Username**: something you know - **PIN**: something you know - **Password**: something you know - **Retina scan**: something you are Susan is using three instances of "something you know" (username, PIN, password) and one instance of "something you are" (retina scan). Therefore, the distinct types of factors she has used are: 1. Something you know (username, PIN, password) 2. Something you are (retina scan) Thus, there are a total of **two distinct types of factors** used. Correct answer: **Two**.