This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Toxicology - 1, Subject name: Forensic Medicine
Heroin is? 
Select and explain. 
A. Cocaine, B. Opioid, C. Dhatura, D. Cannabis
B: Opioid
Answer: B: Opioid 
Explanation: Heroin is diacetyl morphine (semisynthetic form of opium) Classification of opiods: (1) Natural: morphine, codeine.(2) Semi-synthetic: heroin, hydromorphone, oxymorphone, oxycodone. (3) Synthetic: meperidine, methadone, paregoric, diphenoxylate, fentanyl, propoxyphene,levarphanol tarate.