This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Poisoning, Subject name: Forensic Medicine
Widmark's formula helps in the measurement of blood level of - 
Select and explain. 
A. Cocaine, B. Alcohol, C. Barbiturates, D. Benzodiazepines
B: Alcohol
Answer: B: Alcohol 
Explanation: The Widmark formula is provided in equation is a = cpr. Where a = amount of alcohol in grams absorbed in body, c = concentration of alcohol in blood in grams/kg, p = weight of person in kilogram and r = constant. In men, the constant is 0.68 and in women it is 0.55. * For urine analysis, the formula is a = 3/4 qpr. The other factors are same and q = concentration of alcohol in urine in grams/liter. REF;THE SYNOPSIS OF FORENSIC MEDICINE:KS NARAYANA REDDY;28th EDITION;PAGE NO 330