This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pediatrics
Birth weight of a child doubles at five months of age while the birth length doubles at the age of – 
Select and explain. 
A. 1 year, B. 2 years, C. 3 years, D. 4 years
D: 4 years
Answer: D: 4 years 
Explanation: None