Todd has been asked by the security officer to purchase a counter-based authentication system. Which of the following best describes this type of system?

Behavioral biometric systems authenticate users based on dynamic patterns such as keystroke dynamics or gait analysis, not one-time passwords.

Physical biometric systems authenticate using static physical traits such as fingerprints or iris scans, unrelated to OTP generation.

HOTP (RFC 4226) is a counter-based OTP scheme where the client and server share a secret key and maintain a synchronized counter. Each authentication request increments the counter and applies HMAC-SHA1 to the counter plus the secret key to produce a one-time password, which is discarded after use and cannot be replayed.

Passphrase-to-virtual-password systems describe cognitive password schemes or certain legacy password transformations, not counter-synchronized OTP generation.