You Are Part of a Design Team for a GPS

Multiple Choice

You are part of a design team for a GPS system for mountaineers. During user interviews, you notice that most users tend to describe mountain climb difficulty as follows: F Facile (Easy) ; PD Peu Difficile (A little difficult) ; AD Assez Difficile (Fairly difficult) ; D Difficle (Difficult) ; TD Tres Difficile (Very difficult) ; ED Extremement Difficult (Extremely difficult) . What classification system is being used?

A) Location
B) Alphabet
C) Category
D) Hierarchy