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
In dating of bones, which of the following is false 
Select and explain. 
A. In 50 - 100 years, the nitrogen content is more than 3.5 g%, B. Fresh bone shows 15 aminoacids, C. Blood pigments persist upto 100 years, D. Precipitin tests are negative after 5 years
D: Precipitin tests are negative after 5 years
Answer: D: Precipitin tests are negative after 5 years 
Explanation: Dating of bones: - Fresh bone - 4 to 5 g% nitrogen content, In 50 - 100 years, the nitrogen content is more than 3.5 g% - Fresh bone shows 15 aminoacids, more than 100 years - 7 aminoacids - Blood pigments persist upto 100 years - Precipitin tests are negative after 10 years