Mutual authentication for multiple services is also known as
biometrics
multifactor authentication
single-factor authentication
sso

Another name for mutual authentication is also Two factor authentication which is categorized ususlly as the subset of multi factor authentication.

Multi-factor authentication as obvious from the name itself is a way of checking or authenticating he person/user by two or three factors that are known only by him. Multi-factor authentication may includes authentication by:

i do not get the question.