Which of the following is NOT a built-in security feature of Sitefinity?

The selection of data encryption as the option that is NOT a built-in security feature of Sitefinity is grounded in understanding the specific security measures that Sitefinity provides.

Sitefinity indeed supports robust security features such as role-based access control, which allows administrators to control what content users can access based on their assigned roles. User authentication is another key feature, enabling the verification of a user's identity before granting access to the system. Additionally, Sitefinity incorporates protections against common vulnerabilities, helping secure applications against various security threats.

While encryption is an important aspect of data security, Sitefinity does not implement it as a built-in feature. Instead, it requires developers to handle the encryption of sensitive data within applications, utilizing custom solutions or third-party libraries. This distinguishes it from the other options, which are integral to Sitefinity's framework. Thus, data encryption stands out as not being an inherent security feature provided directly by Sitefinity, making it the correct response in this context.