<prompt> All are feature of Autistic disorder EXCEPT:March 2013 b75 mentally retardedUsually appears by 2-3 years of ageAbsent social smileThird person hallucination  <response>: Ans. D i.e. Third person hallucinationAutismDifficulty in concentration and communication,Lesion in frontal and temporal lobe and cerebellum,Delayed speech and language development,Problems in forming social relationships in early childhood,Stereotyped movements,Poor speech,Lack of social interaction, 