This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Nose and paranasal sinuses, Subject name: ENT
[{'content': 'Most common cause of fungal sinusitis is \nSelect and explain. \nA. A. fumigatus, B. A niger, C. A flavus, D. Candida', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Commonest cause of fungal sinusitis is Aspergillus fumigatusOther causes (Non-invasive form) - A.niger, A.flavus, CandidaNon-invasive fungal sinusitis presents as a fungal ball or allergic fungal rhinosinusitis (AFRS)Ref: Hazarika; 3rd ed; Pg 338', 'role': 'assistant'}]