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: Anatomy
If the 4th infralabial is larger than others on either side, the snake may be 
Select and explain. 
A. Cobra, B. Krait, C. Viper, D. Coral snake
B: Krait
Answer: B: Krait 
Explanation: If the 3rd supra labial is not touching eye and nasal shield, then look at the ventral aspect of head. If the 4th infra labial is larger than the others on either side, it is poisonous (krait) Ref: FORENSIC MEDICINE AND TOXICOLOGY Dr PC IGNATIUS THIRD EDITION PAGE 511