This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Miscellaneous (Local and Regional Anesthesia), Subject name: Anaesthesia
[{'content': 'Effect of cocaine on blood vessels is? \nSelect and explain. \nA. Vasoconstrictor, B. Vasodilator, C. Vasoineffective, D. First constrict then dilates', 'role': 'user'}, {'content': 'Answer: A \nExplanation: ANSWER: (A) VasoconstrictorREF: KDT 4th e p. 166Effect of local anesthetic on blood vessels is:VasoconstrictorVasoineffectiveVasodilatorCocaineLignocaineOthers', 'role': 'assistant'}]