What concept is demonstrated by a system that shows which users performed specific actions through recorded transactional information?

The concept demonstrated by a system that shows which users performed specific actions through recorded transactional information is non-repudiation. Non-repudiation ensures that an individual or entity cannot deny the authenticity of their signature on a message or the sending of a message itself. By keeping a record of actions taken by users, such as logs of transactions or audit trails, the system provides evidence that can be used to confirm actions made by specific users. This record serves as a proof of involvement, which can be crucial in resolving disputes or analyzing accountability.

In contrast, privacy relates to the appropriate handling and protection of personal information, ensuring that it is not disclosed without permission. Authentication involves verifying the identity of a user attempting to access a system, while access control refers to the rules and policies governing who can access certain resources and what they can do with them. Non-repudiation, however, specifically focuses on ensuring that actions taken by users are verifiable and attributable to them, reinforcing accountability in information systems.