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: ENT
[{'content': 'Most common sinus involved in acute sinusitis \nSelect and explain. \nA. Ethmoid, B. Maxillary, C. Sphenoid, D. Frontal', 'role': 'user'}, {'content': 'Answer: B \nExplanation: The alveolar process of the maxillae holds the upper teeth and is referred to as the maxillary arch.\nEach maxilla attaches laterally to the zygomatic bones (cheekbones).\nEach maxilla assists in forming the boundaries of three cavities: the roof of the mouth. the floor and lateral wall of the nasal cavity.', 'role': 'assistant'}]