This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Social science, Mental health & Genetics, Subject name: Social & Preventive Medicine
IQ = 20-34 - 
Select and explain. 
A. Severe MR, B. Profound MR, C. Moderate MR, D. Mild MR
A: Severe MR
Answer: A: Severe MR 
Explanation: WHO classification of mental retardation (MR) mild MR ...IQ 50-70 moderate MR....IQ 35-49 severe MR....IQ 20-34 profound MR... IQ undere 20 ref; (page no;582) 23rd edition of PARK&;s textbook of Preventive and Social medicine