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': 'All are pneumatisation patterns of sphenoid sinus except: \nSelect and explain. \nA. Pre sellar, B. Post sellar, C. Concha bullosa, D. Conchal', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Three types of sphenoid sinus pneumatisation patterns are present. Pneumatisation patterns depend on the position of the sinus in relation to the sella turcica (over the body of sphenoid) a. Conchal - no pneumatisation occurs below the sella. There is a solid block of bone beneath the sella. b. Pre sellar - pneumatisation does not extend beyond the anterior border of sella turcica. c. Sellar/Post sellar - In this case pneumatisation occurs both below and posterior to the sella turcica. This is the most common type of sphenoid pneumatisation seen among individuals', 'role': 'assistant'}]