The least expensive and most trustworthy biometric authentication method is ?Retina scanningBadgesAttendence MethodsFingerprint

The least expensive and most trustworthy biometric authentication method generally recognized is Fingerprint Recognition.

Here's a brief analysis of each option:

1. Retina Scanning:

   • Cost: More expensive due to sophisticated technology.
   • Trustworthiness: High accuracy but may require specialized equipment.

2. Badges:

   • Cost: Generally inexpensive but can be forged.
   • Trustworthiness: Lower as they can be lost or copied.

3. Attendance Methods:

   • Cost: Variable, depending on the system used.
   • Trustworthiness: Generally less reliable if based on manual input.

4. Fingerprint Recognition:

   • Cost: Relatively low compared to the high-tech methods like retina scanning.
   • Trustworthiness: High level of uniqueness and can be easily integrated into various systems.

Final Answer

The least expensive and most trustworthy biometric authentication method is Fingerprint Recognition.