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: Pharmacology
[{'content': 'Anti emetic action is produced through :  a) Decreased CTZ stimulation b) H1 agonistic action c) D1 antagonistic action d) Olfactory apparatus stimulation e) 5 HT4 agonistic action \nSelect and explain. \nA. ab, B. ad, C. bc, D. ae', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]