<prompt> IQ49Mild MRModerate MRSevere MRProfound MR  <response>: WHO classification of Mental retardationMR mild MR...IQ 50-70 moderate MR ...35-49 severe MR..IQ 20-34 profound MR...IQ under 20 ref; page no;637 25th edition of PARKs textbook of Preventive and Social medicine 