Which of the following poisoning is demonstrated by Kunkel's test?

Kunkel's test or tannic acid test: If tannic acid is added to blood it remains cherry-red in CO poisoning, where oxyhemoglobin turns deep brown. Hoppe-Seyler's test is also used to identify CO poisoning. Few drops of blood are added to a solution of 10% sodium hydroxide. Normal blood turns brownish-green, but if CO is present, the color will remain pink. Ref: The Essentials of Forensic Medicine and Toxicology by KS Narayan Reddy, 27th edition, Page 555.