The three classic ways of authenticating yourself to the computer security software are by something you know, by something you have, and by something: 

Answer options:

A. you need.
B. non-trivial
C. you are.
D. you can get.

C

This is more commonly known as biometrics and is one of the most accurate ways to authenticate an individual. The rest of the answers are incorrect because they not one of the three recognized forms for Authentication.