Why Is Classification a Necessary First Step in Developing an Understanding

Why is classification a necessary first step in developing an understanding about abnormal behavior?

A) Communication about abnormal behavior can not be effective unless what is being discussed is clear.
B) Only through development of a classification system can abnormal and normal behavior be differentiated.
C) Unless an adequate classification system exists, all descriptions of abnormality will necessarily be subjective.
D) Abnormal behavior is not abnormal until it has been classified as such.