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: Surgery
[{'content': 'Increased incidence of reaction to L.A will occur by \nSelect and explain. \nA. Rapid rate of injection, B. Using an aspirating technique, C. Addition of vaso constrictor to the solution, D. Premedication with barbiturate', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]