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.
B) overtime, any given word can disappear from a language or acquire a new meaning.
The teachers present at the teacher's lounge could be there for a variety of reasons, for example it could even me a meeting of the supporters of the school uniform! his sample is therefore possibly biased - there is no way of knowing that it represents the whole population. He chose it because it was convenient to him - and the answer is "a, convenience sampling"
