Answer: Mutual Authentication.
Explanation:
Mutual Authentication also referred to as "two way authentication" is a process/technology by which two entities authenticates each other mutually in a link of communication. Here, server and client authentication are combined that is the client authenticates the server and the server authenticates the client. Client trusts the digital certificate of the server and in turn, server trusts the certificate of the client. Transport Layer Security (TLS) protocol is a means by which exchange of certificate is carried out. The certificate with the current timestamp is used to authenticate the client to the server if the client has more than one certificate.
D. It is a direct quote and cited correctly
