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': 'Objective signs of inferior alveolar nerve block are seen in \nSelect and explain. \nA. Unilateral midline between premolars & incisors, B. Bilaterally between premolar & incisors, C. Unilateral midline between 2nd molar & incisor, D. Bilateral midline between 2nd molar & incisor', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]