A person is brought to you with suspicion of driving under the influence of alcohol. Assuming that all the facilities are available for alcohol level estimation, which of the following is the MOST desirable test for alcohol estimation?

Though all of the above are methods of estimation of alcohol levels, gas chromatography is the most specific. Breath analysis is the method commonly used by highway police. Cavett test involves distillation of the alcohol which is oxidised to acetic acid. It is also used for estimation of blood alcohol levels. Ref: Textbook of Forensic Medicine and Toxicology by Narayan Reddy, Edition 23, Page - 484, 485.