Which Summary of Research Best Exemplifies Co-Morbidity

Which summary of research best exemplifies co-morbidity?

A) Studies support the conclusion that borderline personality disorder and agoraphobia should be recognized as a single disorder.
B) Studies support the conclusion that avoidant personality disorder is one of the leading causes of suicidal behavior.
C) Studies suggest that many individuals with obsessive-compulsive disorder suffer from Tourette's syndrome as well.
D) Studies suggest that many cases of schizotypal personality disorder are misdiagnosed as schizophrenia.