This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Autonomic nervous system, Subject name: Pharmacology
[{'content': 'Lid retraction is caused by? \nSelect and explain. \nA. Bimatoprost, B. Latanoprost, C. Brimonidine, D. Apraclonidine', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Ref:KD Tripathi pharmacology 7th edition (page.no: 154) Apraclonidine causes eyelid retraction due to stimulation of a1 receptor. Brimonidine cause less prominent lid retraction due to weaker a1 activity Ref-Drug facts and comparison 2006/2257', 'role': 'assistant'}]