TLS does not require mutual authentication. Only server must authenticate its public key to the client. Client is authenticated by the application via a password. The most common way for public key authentication would be a. a photo ID. b. a password. c. a certificate. d. biometrics.

c. a certificate.

Explanation:

Public key infrastructure authentication is intended to make transactions occurring through the internet as secure as possible. Public keys are usually assigned to entities like business firms or individuals, and digital certificates are given to them as proof that they have been authenticated.

A certificate authority has the role of signing, storing, and issuing digital certificates. A software or humans could be charged with the responsibility of actually ensuring a key to user binding if all conditions are satisfied.