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': 'Cillia can transport radiolabelled particle in antrum with: \nSelect and explain. \nA. 1-20dm/min, B. 20-30mm/sec, C. 1-20mm/ min., D. 20-30mm/min', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Cilia can transport radiolabeled particles an average of 6mm/min, with a range of 1-20mm/min. Thus this transport can clear inhaled particles from nasal cavity in 10-20 min.', 'role': 'assistant'}]