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=49 
Select and explain. 
A. Mild MR, B. Moderate MR, C. Severe MR, D. Profound MR
B: Moderate MR
Answer: B: Moderate MR 
Explanation: WHO classification of Mental retardation(MR) 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 PARK's textbook of Preventive and Social medicine