This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Miscellaneous (Pharmacology), Subject name: Pharmacology
[{'content': 'Patient intoxicated himself with two bottles of nasal decongestant whose primary ingredient was alpha agonist drug. Which is earliest sign seen? \nSelect and explain. \nA. Tachycardia, B. Dilatation of pupil, C. Vasodilation, D. All of the above', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans. B. Dilatation of pupilStimulation of alpha receptors causes dilation of pupil. Whereas tachycardia and vasodilation are due to beta receptor stimulation.', 'role': 'assistant'}]