Which of the following options is NOT a valid authentication method?

The choice that is not a valid authentication method is manual identity verification via spreadsheet. This approach lacks the necessary security controls and technological framework typically associated with effective authentication methods.

Authentication methods are designed to verify the identity of users before granting them access to systems or data. Effective authentication mechanisms include those that provide strong security, are resistant to forgery or manipulation, and can be consistently applied across users and sessions.

Password-based authentication combined with multi-step verification enhances security by requiring additional proof of identity beyond just a password. Biometric authentication methods utilize unique physical characteristics of a user, such as fingerprints or facial recognition, ensuring a high level of accuracy and security. Smartcard access systems involve the use of physical cards that securely store user credentials and can often incorporate additional cryptographic measures for secure access.

In contrast, manual identity verification via spreadsheet is highly susceptible to errors and can easily be manipulated. It does not provide the automated, secure, and verifiable means of establishing identity that other methods do, hence making it an inadequate choice for authentication purposes.