This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Toxicology, Subject name: Forensic Medicine
Marking nut is 
Select and explain. 
A. Semicarpus anacardium, B. Croton tiglium, C. Areca catechu, D. Abrus precatorius
A: Semicarpus anacardium
Answer: A: Semicarpus anacardium 
Explanation: Ans. is 'a' i.e., Semicarpus anacardium Semicarpus anacardium (marking nut or bhilawan)* Its seed are heart shaped, conical and black with acrid oily juice which is brownish but turns black on exposure to air. Active principles are semecarpol and bhilawanol.* Juice applied to skin produces irritation, painful blisters followed by itching and eczema. Therefore it is used to produce artificial bruises.* It is also used by washerman to mark clothes.