This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Central Neuraxial Blockade, Subject name: Anaesthesia
Which of the following are features of opioid withdrawal? 
Select and explain. 
A. Constipation, bradycardia, coma, B. Abdominal cramps, vomiting, insomnia, C. Hypehermia, vomiting, restlessness, D. Hypothermia , nausea , constipation
B: Abdominal cramps, vomiting, insomnia
Answer: B: Abdominal cramps, vomiting, insomnia 
Explanation: - Physical dependence on morphine usually requires about 25 days to develop but may occur sooner in emotionally unstable persons. - When physical dependence is established, discontinuation of opioid agonist produces a typical withdrawal abstinence syndrome. - Initial symptoms of withdrawal include yawning, diaphoresis, lacrimation, or coryza. - Insomnia & restlessness are prominent. - Abdominal cramps, nausea, vomiting & diarrhea reach their peak in 72 hours & then decline over the next 7 to 10 days. - During withdrawal, tolerance to morphine is rapidly lost & syndrome can be terminated by a modest dose of opioid agonist.