This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Growth and development, Subject name: Pediatrics
The height of a child is double the bih height at the age of _________ 
Select and explain. 
A. 1 year, B. 2 years, C. 4 years, D. 6 years
C: 4 years
Answer: C: 4 years 
Explanation: The infant measures approximately 50cm at bih, 60cm at 3 months, 65cm at 6 months, 70 cm at 9 months, 75cm at 1 yr and 90cm at 2 yr. A normal Indian child is 100cm tall at the age of 4 yr. Thereafter, the child gains about 6cm in height every year, until the age of 12 yr. After this, increments in height vary according to the age at the onset of pubey Ref : Essential pediatrics, op ghai , 8th edition pg no:13.