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: Forensic Medicine
In case of chronic lead poisoning, the levels of which of the following is elevated: NIMHANS 11 
Select and explain. 
A. Porphobilinogen, B. 6-amino levulinic acid, C. Bilirubin, D. Urobilinogen
B: 6-amino levulinic acid
Answer: B: 6-amino levulinic acid 
Explanation: Ans. 6-amino levulinic acid