This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Forensic Medicine
Usual sign of opioid withdrawal: PGI 13 
Select and explain. 
A. Stupor, B. Constipation, C. Constricted pupil, D. Yawning
D: Yawning
Answer: D: Yawning 
Explanation: Ans. Yawning