This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Human identification, Subject name: Forensic Medicine
Sacrum becomes a single bone at ___ years of age.:- 
Select and explain. 
A. 15, B. 25, C. 30, D. 40
B: 25
Answer: B: 25 
Explanation: Sacrum The five sacral veebrae are separated by cailage until pubey. Later, fusion of epiphyses takes place and ossification of interveebral discs extend from below upwards. Sacrum becomes single bone at 21-25 years of age. Sometimes, it leaves a gap between S1 and S2, until 32 years called as 'lapsed union'.