Answer: D) a personality disorder.
Explanation:
Personality disorder is known to be a mental illness or disorder which makes an individual to exhibit certain behaviours which are harmful to his or her health for a long period of time. It affects how an individual think, act and associate with people around him or her and is characterized by behaviours and thoughts which are not in conformity to culture and custom of the society. Thus, an individual with this type of disorder avoid social gathering and activities, sees her behaviours and actions as normal and so on.