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
Kunkel's test is done to demonstrate presence of ................. in blood. 
Select and explain. 
A. Lead, B. CuSO4, C. CO, D. Dhatura
C: CO
Answer: C: CO 
Explanation: Carbon monoxide (CO)