This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Intravenous Anesthetic Agents, Subject name: Anaesthesia
The following are used for treatment of postoperative nausea and vomiting following squint surgery in children except:- 
Select and explain. 
A. Propofol, B. Ketamine, C. Dexamethasone, D. Ondansetron
B: Ketamine
Answer: B: Ketamine 
Explanation: ketamine does not have antiemetic effect, among anaesthetic agent propofol has antiemetic effect. even benzodiazepine has antiemetic effect , midazolam has best antiemetic effect among them.