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: Dental
[{'content': 'A 25 year old male comes with a complaint of throbbing pain in the upper part of the cheek or entire side of face, heavy feeling in the face, which exacerbates on bending down and with associated pyrexia. The most probable diagnosis is \nSelect and explain. \nA. Acute dento alveolar abscess in relation to upper first molar., B. Irreversible pulpitis in relation to upper 2nd molar., C. Acute maxillary sinusitis, D. Acute periodontal abscess in relation to upper 1st molar', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]