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
Chronological age 10 yrs, mental age 4 yrs. What that person called as ? 
Select and explain. 
A. Idiot, B. Imbecile, C. Normal, D. Genius
B: Imbecile
Answer: B: Imbecile 
Explanation: IQ =mental age /chronological age *100 mental age -4, chronological age -10 4/10 *100 = 40 level of intelligence IQ range idiot 0-24 imbecile 25-49 moron 50-69 borderline 70-79 low normal 80-89 normal 90-109 superior 110-119 very superior 120-139 near genius 140 and above ref ;(page no;679)23rd edition of PARK&;s textbook of Preventive and Social medicine