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': 'Xylometazoline nasal drops given before nasotracheal intubation to \nSelect and explain. \nA. Vasoconstriction of nasal mucosa, B. Dilatation of orifices, C. Decrease secretion, D. Dilation of posterior', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]