<prompt> Delirium is defined as ?Acute onset of disturbed consciousnessChronic onset of disturbed consciousnessProgressive generalized impairment of intellectual functions and memory without impairment of consciousnessDisorientation without clouding of consciousness  <response>: Ans. A. Acute onset of disturbed consciousnessDelirium is defined by the acute onset of fluctuating cognitive impairment and a disturbance of consciousness.It is also referred to as acute confusional state or acute organic brain syndrome. 