Which of the following tests validates access for existing user accounts?

User Account Validation is the appropriate choice as it specifically focuses on the verification of access for existing user accounts. This process involves checking that users who currently possess accounts are being granted access according to the policies and controls set by the organization. It helps to ensure that access permissions align with the user's role and responsibilities and that no unauthorized changes have been made to their accounts.

This validation can involve auditing existing accounts to confirm that they are still needed, ensuring that they have the correct access rights, and that any changes in personnel or role adjustments are appropriately reflected in the access permissions. By conducting a user account validation, organizations can prevent unauthorized access and mitigate potential security risks associated with inactive or improperly managed accounts.