Final answer:
The core feature characterizing personality disorders is 'c) significant interpersonal problems.' This reflects the pervasive difficulties individuals with these disorders experience in personal and social interactions.
Step-by-step explanation:
Personality disorders are characterized by enduring and inflexible patterns of behavior and thought that deviate significantly from societal expectations. These patterns are pervasive and lead to significant distress or impairment in personal, social, and/or occupational situations. The core feature that characterizes personality disorders in the context of this quiz question would be significant interpersonal problems. Disturbed thought processes are more characteristic of psychotic disorders, whereas multiple identities or personalities are related to dissociative identity disorder. Difficulty using language to communicate is not a core feature of personality disorders but is more associated with communication disorders.
The correct answer to the question is c) significant interpersonal problems. Personality disorders such as Borderline Personality Disorder and Narcissistic Personality Disorder are especially known for their impact on personal relationships and the ability to function well in social settings. It's important to use the Diagnostic and Statistical Manual of Mental Disorders (DSM) as a guide for diagnosis and classification of these disorders, despite the nuances and evolving nature of these classifications.