Final answer:
For a diagnosis of schizoid personality disorder, the key symptom to look for is a lack of close relationships. Individuals with this disorder typically exhibit social detachment and limited emotional expression in interpersonal settings.
Step-by-step explanation:
To confirm a diagnosis of schizoid personality disorder, you would look for a lack of close relationships, as the correct answer is D. Lack of close relationships. Individuals with schizoid personality disorder often display a pattern of detachment from social relationships and a restricted range of emotional expression with others. They typically do not desire or enjoy close relationships, including being part of a family. This disorder is different from schizophrenia and should not be confused with conditions characterized by paranoia, grandiosity, magical thinking, or bright clothing, which are not generally associated with schizoid personality disorder.