Which feature prevents members of the sysadmin role from viewing data values in a table?

The feature that effectively prevents members of the sysadmin role from viewing data values in a table is Always Encrypted. This technology is designed to encrypt sensitive data within SQL Server databases, ensuring that the data remains encrypted during storage and usage. With Always Encrypted, the encryption keys are managed on the client side rather than the server side, meaning that the database engine cannot decrypt the underlying data.

By utilizing this feature, sensitive information, such as personal identification numbers or credit card details, can be protected from even those who have administrative privileges on the database server, like sysadmin role members. This ensures that sensitive data is only accessible by authorized applications or users who have the appropriate encryption keys.

In contrast, other options like Row-level security, Data masking, and Transparent data encryption serve different purposes in data protection and access control. Row-level security restricts access to specific rows of data based on user roles, but it does not hide data values from sysadmins. Data masking alters the data values to obscure sensitive information but allows sysadmins to still see the underlying data in its original form if they have the necessary access. Transparent data encryption secures data at rest through encryption of the database files themselves but does not prevent privileged users from accessing the plaintext data.