Kat needs comprehensive and accurate information about several psychological disorders for her research. Why is the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV-TR) a good reference for Kat's research?

A. This manual contains careful descriptions of the symptoms of different disorders.
B. This manual provides a deep understanding of the causes and treatments of different psychological disorders.
C. This manual helps people with psychological disorders treat themselves.
D. This manual is a combination of theories and myths about different psychological disorders.