The psychopathology of Delusion is associated with a disorder of which of the following?

Delusions are fixed false beliefs, which are held against any evidence challenge. Hallucinations and illusions are disorders of perception or perceptual abnormalities. Delirium and dementia are disorders of cognition. 'Lack of insight' is unawareness of the illness and is a symptom of psychotic disorders. Ref: Kaplan & Sadock's Synopsis of Psychiatry 9th Edition, Page 281- 83; Neeraj Ahuja 5Th Edition, Page 86 4Th Edition, Page 13; Current Diagnosis & Treatment In Psychiatry Page 95-113; Shoer Oxford Textbook of Psychiatry 5Th Edition, Page 2-20