Which of the following security mechanisms provides evidence that can be used to prove a specific action or event took place?

The correct answer is B. Non-repudiation.

Explanation: Non-repudiation is a security mechanism that ensures that an individual or entity cannot deny the authenticity of their signature on a document or a sent message. It provides evidence that a specific action or event, such as the sending of a message or the completion of a transaction, took place. This is often achieved through the use of digital signatures and secure logs, allowing for accountability and verification of actions.