To solve this question, the user needs to know the definitions of different security concepts and their applications. The user must identify the concept that refers to the testing or reconciliation of evidence of a user's identity.
Now, let's go through each option and explain why it is right or wrong:
A. Authorization: Authorization refers to the process of granting or denying access to a resource based on a user's identity and the permissions associated with that identity. This option is not the correct answer since it does not refer to the testing or reconciliation of evidence of a user's identity.
B. Accountability: Accountability refers to the state of being responsible or answerable for one's actions. This option is not the correct answer since it does not refer to the testing or reconciliation of evidence of a user's identity.
C. Auditing: Auditing refers to the process of tracking and evaluating the use of resources or actions taken by users to ensure compliance with policies and regulations. This option is not the correct answer since it does not refer to the testing or reconciliation of evidence of a user's identity.
D. Authentication: Authentication refers to the process of verifying the identity of a user or system. This includes the testing or reconciliation of evidence of a user's identity such as passwords, biometric data, or security tokens. This option is the correct answer.
Therefore, the answer is: D. Authentication.