Given What Is Known About Illnesses Such as Post-Traumatic Stress

Given what is known about illnesses such as post-traumatic stress disorder becoming included in the Diagnostic and Statistical Manual of Psychiatric Disorders (DSM) ,which of the following often means the difference between inclusion and exclusion,over and above simple physical or mental symptomology?

A) the success of political lobbying efforts
B) the weight of evidence presented by science
C) the amount of money contributed to the American Psychiatric Association
D) the broad social class base of people who exhibit the symptoms