IQ in profound mental retardation -

Ans. is 'd' i.e., < 20 The Intelligence Quotient (I.Q.) is calculated according to the formula:IQ =Mental age----------------Chronological agex 100The WHO classification of mental retardation is based on the concept of IQ and includes the following categories:CategoryIQMild50-70Moderate35-49Severe20-34Profound<20A child with IQ < 70 is called mentally retarded.