Answer: This means that A. they have irrational shame because of it.
Explanation: The word "stigma" is generally used to refer to something that makes people feel ashamed. Moreover, a stigma is associated, in some cases, with something that an individual might feel it could harm his/her good reputation. In that way, the fact that psychological disorders carry a stigma for some people means that some individuals feel unfair disapproval towards psychological disorders and that they have irrational shame because of them. Sometimes, people even tend to avoid talking about psychological disorders due to this feeling of shame.